Gravitation Class 11 Notes | NEET Physics Complete Guide<\/title>\n<meta name=\"description\" content=\"Complete Gravitation class 11 notes for NEET Physics. Covers Kepler's laws, Newton's law, escape velocity, orbital velocity, satellites, and variation of g with formulas and PYQs.\">\n<link rel=\"preconnect\" href=\"https:\/\/fonts.googleapis.com\">\n<link rel=\"preconnect\" href=\"https:\/\/fonts.gstatic.com\" crossorigin>\n<link href=\"https:\/\/fonts.googleapis.com\/css2?family=Plus+Jakarta+Sans:wght@400;500;600;700;800&family=DM+Sans:ital,wght@0,300;0,400;0,500;0,600;1,400&family=JetBrains+Mono:wght@400;500;600&display=swap\" rel=\"stylesheet\">\n<style>\n *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }\n\n :root {\n --accent: #e8600a;\n --accent-light: #fff3ec;\n --accent-mid: #ffd9bf;\n --dark: #111827;\n --text: #1a1a1a;\n --text-muted: #555;\n --border: #e5e7eb;\n --tip-bg: #eff6ff;\n --tip-border: #3b82f6;\n --warn-bg: #fff3ec;\n --warn-border: #e8600a;\n --green-bg: #f0fdf4;\n --green-border: #22c55e;\n --green-text: #166534;\n }\n\n body {\n font-family: 'DM Sans', sans-serif;\n color: var(--text);\n background: #fff;\n font-size: 16px;\n line-height: 1.75;\n margin: 0;\n padding: 0;\n }\n\n article {\n width: 100%;\n padding: 0;\n margin: 0;\n }\n\n \/* \u2500\u2500 SECTION \u2500\u2500 *\/\n .section {\n padding: 52px 0;\n margin: 0;\n border-bottom: 1px solid var(--border);\n }\n .section:last-of-type { border-bottom: none; 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margin: 0; color: #7c2d12; }\n\n \/* \u2500\u2500 CONTENT LIST \u2500\u2500 *\/\n ul.content-list {\n padding-left: 0;\n list-style: none;\n margin: 14px 0;\n display: grid;\n gap: 8px;\n }\n ul.content-list li {\n padding-left: 22px;\n position: relative;\n font-size: 15px;\n }\n ul.content-list li::before {\n content: '';\n position: absolute;\n left: 0; top: 9px;\n width: 8px; height: 8px;\n background: var(--accent);\n border-radius: 50%;\n }\n\n \/* \u2500\u2500 TWO COLUMN \u2500\u2500 *\/\n .two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; margin: 20px 0; }\n @media (max-width: 640px) { .two-col { grid-template-columns: 1fr; } .cta-section { padding: 48px 0; } }\n\n a { color: var(--accent); }\n strong { font-weight: 600; }\n\n .pyq-badge {\n display: inline-block;\n background: #fef3c7;\n border: 1px solid #fbbf24;\n color: #92400e;\n font-size: 11px;\n font-weight: 700;\n padding: 2px 8px;\n border-radius: 4px;\n font-family: 'Plus Jakarta Sans', sans-serif;\n letter-spacing: 0.5px;\n text-transform: uppercase;\n margin-right: 8px;\n }\n<\/style>\n<\/head>\n<body>\n<article>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">01<\/div>\n <h2 class=\"section-title\">Introduction to <span>Gravitation<\/span><\/h2>\n <\/div>\n\n <p>These <strong>Gravitation class 11 notes<\/strong> cover one of the most conceptually rich and NEET-relevant chapters in Class 11 Physics. Gravitation is the universal force of attraction that acts between every two objects possessing mass. It governs why an apple falls to the ground, why the Moon orbits Earth, why planets trace elliptical paths around the Sun, and how satellites remain in orbit. Unlike contact forces, gravitation acts across empty space over unlimited distances \u2014 making it the dominant force at cosmic scales.<\/p>\n\n <p>The chapter progresses from Kepler’s observational laws through Newton’s quantitative formulation, to modern applications in satellite technology. Every concept introduced here has direct NEET application, and the formulas are closely inter-linked \u2014 escape velocity, orbital velocity, gravitational potential energy, and g-variation all derive from Newton’s single law of gravitation.<\/p>\n\n <div class=\"highlight-grid\">\n <div class=\"highlight-card\">\n <div class=\"hc-title\">Chapter Scope<\/div>\n <p>From falling bodies on Earth to orbiting satellites and planetary motion.<\/p>\n <\/div>\n <div class=\"highlight-card\">\n <div class=\"hc-title\">NEET Weightage<\/div>\n <p>2\u20134 questions per year. Consistent, high-scoring chapter for prepared students.<\/p>\n <\/div>\n <div class=\"highlight-card\">\n <div class=\"hc-title\">Key Concept<\/div>\n <p>One universal law \u2014 Newton’s law \u2014 generates all other formulas in this chapter.<\/p>\n <\/div>\n <\/div>\n\n <div class=\"related-links\">\n <h4>Related Resources<\/h4>\n <ul>\n <li><a href=\"https:\/\/ksquareinstitute.in\/blog\/neet-physics-survival-kit-2026\/\">NEET Physics Survival Kit<\/a><\/li>\n <li><a href=\"https:\/\/ksquareinstitute.in\/blog\/organic-chemistry-strategy-neet\/\">Organic Chemistry Strategy<\/a><\/li>\n <li><a href=\"https:\/\/ksquareinstitute.in\/blog\/neet-biology-tricks-for-exams\/\">NEET Biology Tricks for Exams<\/a><\/li>\n <li><a href=\"https:\/\/ksquareinstitute.in\/blog\/score-340-in-neet-biology\/\">How to Score 340+ in NEET Biology<\/a><\/li>\n <li><a href=\"https:\/\/ksquareinstitute.in\/blog\/top-10-tricky-neet-biology-diagrams\/\">Top 10 Tricky NEET Biology Diagrams<\/a><\/li>\n <li><a href=\"https:\/\/ksquareinstitute.in\/free-study-material\/\">Free Study Materials<\/a><\/li>\n <\/ul>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">02<\/div>\n <h2 class=\"section-title\">Kepler’s Laws of <span>Planetary Motion<\/span><\/h2>\n <\/div>\n\n <p>Before Newton derived his law analytically, Johannes Kepler established three empirical laws by meticulously analyzing Tycho Brahe’s observational data on planetary positions. These laws describe the geometry and timing of planetary orbits with precision.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Kepler’s Three Laws<\/div>\n <code>Law 1 (Orbits): All planets move in elliptical orbits with the Sun at one focus.<\/code>\n <code>Law 2 (Areas): A line joining a planet to the Sun sweeps equal areas in equal times.<\/code>\n <code>Law 3 (Periods): T\u00b2 \u221d r\u00b3 \u27f9 T\u00b2\/r\u00b3 = constant for all planets<\/code>\n <\/div>\n\n <p><strong>Law 2 (equal areas)<\/strong> is a direct consequence of conservation of angular momentum \u2014 no external torque acts on the planet-Sun system, so L = mvr is conserved. When the planet is closer (perihelion), r is small, so v must be large. When farther (aphelion), v is smaller.<\/p>\n\n <p><strong>Law 3<\/strong> is the most quantitatively useful for NEET. It allows comparison of orbital periods and radii: if Earth’s period is 1 year at 1 AU, Jupiter’s period can be calculated from its orbital radius alone.<\/p>\n\n <div class=\"callout callout-tip\">\n <span class=\"callout-icon\">Tip<\/span>\n <p>For NEET, Kepler’s third law T\u00b2 \u221d r\u00b3 is tested by giving two planets’ orbital radii and asking for the ratio of their time periods. Apply (T\u2081\/T\u2082)\u00b2 = (r\u2081\/r\u2082)\u00b3 directly.<\/p>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">03<\/div>\n <h2 class=\"section-title\">Newton’s Law of <span>Universal Gravitation<\/span><\/h2>\n <\/div>\n\n <p>Newton unified terrestrial and celestial mechanics with a single quantitative statement: <strong>every particle in the universe attracts every other particle with a force proportional to the product of their masses and inversely proportional to the square of the distance between them.<\/strong> The force acts along the line joining their centres.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Newton’s Law of Gravitation<\/div>\n <code>F = G \u00d7 m\u2081 \u00d7 m\u2082 \/ r\u00b2<\/code>\n <code>F = gravitational force (N)<\/code>\n <code>G = 6.674 \u00d7 10\u207b\u00b9\u00b9 N\u00b7m\u00b2\/kg\u00b2 (gravitational constant)<\/code>\n <code>m\u2081, m\u2082 = masses of the two bodies (kg)<\/code>\n <code>r = distance between their centres (m)<\/code>\n <\/div>\n\n <p>Key properties of gravitational force:<\/p>\n <ul class=\"content-list\">\n <li>Always attractive \u2014 never repulsive between masses.<\/li>\n <li>Acts along the line joining the two bodies (central force).<\/li>\n <li>Obeys Newton’s third law: F\u2081\u2082 = \u2212F\u2082\u2081 (equal in magnitude, opposite in direction).<\/li>\n <li>Independent of the medium between the two bodies.<\/li>\n <li>Follows superposition: total force on a body is the vector sum of individual gravitational forces from all other bodies.<\/li>\n <\/ul>\n\n <div class=\"callout callout-warn\">\n <span class=\"callout-icon\">Warning<\/span>\n <p>Newton’s law applies to point masses or uniform spheres. For a uniform sphere, the entire mass can be assumed concentrated at the centre \u2014 valid only outside the sphere. Inside a uniform sphere, only the mass enclosed within the radius contributes to the force.<\/p>\n <\/div>\n<\/div>\n\n\n<a href=\"https:\/\/courses.ksquare.co.in\/new-courses\/3-mission-180-neet-physics-rankers-batch\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" style=\"display:block; margin-bottom:20px;\">\n <img decoding=\"async\" src=\"https:\/\/ksquareinstitute.in\/blog\/wp-content\/uploads\/2026\/03\/Course-Poromo-Banner-scaled.png\" alt=\"Mission 180 NEET Physics Rankers Batch - KSquare Career Institute\" style=\"width:100%; height:auto; border-radius:10px; display:block;\">\n<\/a>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">04<\/div>\n <h2 class=\"section-title\">Gravitational Constant <span>(G)<\/span><\/h2>\n <\/div>\n\n <p>The gravitational constant G is a fundamental physical constant that quantifies the strength of the gravitational interaction. Its value is extraordinarily small, which is why gravitational forces between everyday objects are negligible \u2014 only astronomical masses make gravity perceptible.<\/p>\n\n <div class=\"formula-orange\">\n <div class=\"f-label\">Value and Dimensions of G<\/div>\n <code>G = 6.674 \u00d7 10\u207b\u00b9\u00b9 N\u00b7m\u00b2\u00b7kg\u207b\u00b2<\/code>\n <code>Dimensional formula: [M\u207b\u00b9 L\u00b3 T\u207b\u00b2]<\/code>\n <code>G is a scalar quantity; same value throughout the universe.<\/code>\n <\/div>\n\n <p>G was first measured experimentally by Henry Cavendish in 1798 using a torsion balance apparatus (the Cavendish experiment). Two small lead spheres were attracted to two large lead spheres, and the tiny twist in the suspension wire allowed G to be calculated. G does not vary with temperature, pressure, medium, or location \u2014 it is a true universal constant.<\/p>\n\n <div class=\"callout callout-tip\">\n <span class=\"callout-icon\">Tip<\/span>\n <p>Do not confuse G (universal gravitational constant, 6.674 \u00d7 10\u207b\u00b9\u00b9) with g (acceleration due to gravity, ~9.8 m\/s\u00b2). G is universal and constant; g varies with location and is derived from G, M, and R of the planet.<\/p>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">05<\/div>\n <h2 class=\"section-title\">Acceleration Due to <span>Gravity (g)<\/span><\/h2>\n <\/div>\n\n <p>When an object is in free fall near Earth’s surface, it accelerates at a rate determined by Earth’s gravitational pull. This acceleration, called <strong>g<\/strong>, is derived by equating Newton’s gravitational force to Newton’s second law of motion.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Derivation of g<\/div>\n <code>Gravitational force: F = GMm\/R\u00b2<\/code>\n <code>Newton's 2nd law: F = mg<\/code>\n <code>Therefore: g = GM\/R\u00b2<\/code>\n <code>g_Earth \u2248 9.8 m\/s\u00b2 (standard value at surface)<\/code>\n <code>M = mass of Earth = 6 \u00d7 10\u00b2\u2074 kg<\/code>\n <code>R = radius of Earth = 6.4 \u00d7 10\u2076 m<\/code>\n <\/div>\n\n <p>Note that g is independent of the mass of the falling body \u2014 all objects regardless of mass fall with the same acceleration in a vacuum. This is the equivalence principle, foundational to Einstein’s General Theory of Relativity.<\/p>\n\n <div class=\"callout callout-warn\">\n <span class=\"callout-icon\">Warning<\/span>\n <p>The formula g = GM\/R\u00b2 gives the surface value of g. At altitude h or depth d, the formula changes. Never use the surface formula when the problem specifies a location above or below Earth’s surface.<\/p>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">06<\/div>\n <h2 class=\"section-title\">Variation of g \u2014 Altitude, Depth, <span>and Latitude<\/span><\/h2>\n <\/div>\n\n <p>The value of <strong>g<\/strong> is not constant \u2014 it varies with position on or above Earth. Understanding these variations is critical for <strong>Gravitation class 11 notes<\/strong> and appears frequently in NEET numericals.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Variation with Altitude (h above surface)<\/div>\n <code>g_h = g(1 \u2212 2h\/R) for h << R (approximate)<\/code>\n <code>g_h = GM\/(R + h)\u00b2 (exact formula)<\/code>\n <code>g decreases with increasing altitude.<\/code>\n <\/div>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Variation with Depth (d below surface)<\/div>\n <code>g_d = g(1 \u2212 d\/R)<\/code>\n <code>At the centre of Earth (d = R): g_d = 0<\/code>\n <code>g decreases linearly with depth inside Earth.<\/code>\n <\/div>\n\n <div class=\"formula-orange\">\n <div class=\"f-label\">Variation with Latitude (\u03c6)<\/div>\n <code>g_\u03c6 = g \u2212 R\u03c9\u00b2cos\u00b2\u03c6<\/code>\n <code>g is maximum at poles (\u03c6 = 90\u00b0, cos \u03c6 = 0)<\/code>\n <code>g is minimum at equator (\u03c6 = 0\u00b0, cos \u03c6 = 1)<\/code>\n <code>\u03c9 = angular velocity of Earth's rotation<\/code>\n <\/div>\n\n <div class=\"table-wrap\">\n <table>\n <thead>\n <tr>\n <th>Factor<\/th>\n <th>Effect on g<\/th>\n <th>Rate of Change<\/th>\n <\/tr>\n <\/thead>\n <tbody>\n <tr>\n <td>Altitude (h above surface)<\/td>\n <td>Decreases<\/td>\n <td>Inversely with (R + h)\u00b2<\/td>\n <\/tr>\n <tr>\n <td>Depth (d below surface)<\/td>\n <td>Decreases linearly<\/td>\n <td>g_d = g(1 \u2212 d\/R)<\/td>\n <\/tr>\n <tr>\n <td>Latitude (towards poles)<\/td>\n <td>Increases<\/td>\n <td>g_pole > g_equator by ~0.05 m\/s\u00b2<\/td>\n <\/tr>\n <tr>\n <td>Rotation of Earth<\/td>\n <td>Reduces effective g<\/td>\n <td>Effect maximum at equator<\/td>\n <\/tr>\n <\/tbody>\n <\/table>\n <\/div>\n\n <div class=\"callout callout-warn\">\n <span class=\"callout-icon\">Warning<\/span>\n <p>A classic NEET trap: g at height h equals g at depth d does NOT mean h = d. The altitude formula has a squared term (exact) or a factor of 2 (approximate), while the depth formula is linear. For the approximate case: g(1 \u2212 2h\/R) = g(1 \u2212 d\/R) gives d = 2h.<\/p>\n <\/div>\n<\/div>\n\n\n<a href=\"https:\/\/ksquareinstitute.in\/neet-2026-rank-predictor\/\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" style=\"display:block; margin-bottom:20px;\">\n <img decoding=\"async\" src=\"https:\/\/ksquareinstitute.in\/blog\/wp-content\/uploads\/2026\/03\/neet-2026-college-and-rank-predictor-scaled.png\" alt=\"NEET 2026 College and Rank Predictor - KSquare Career Institute\" style=\"width:100%; height:auto; border-radius:10px; display:block;\">\n<\/a>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">07<\/div>\n <h2 class=\"section-title\">Gravitational <span>Potential Energy<\/span><\/h2>\n <\/div>\n\n <p>Gravitational potential energy (U) is the work done by an external agent in moving a mass from infinity to a given point in the gravitational field, without any change in kinetic energy. Because gravity is attractive and does positive work as the mass approaches, the external agent does negative work \u2014 hence U is always negative for gravitational systems.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Gravitational Potential Energy<\/div>\n <code>U = \u2212GMm\/r<\/code>\n <code>U \u2192 0 as r \u2192 \u221e (reference point at infinity)<\/code>\n <code>Near Earth's surface: U = mgh (for small h, approximate)<\/code>\n <code>Change in PE: \u0394U = mgh (valid only near surface where g is constant)<\/code>\n <\/div>\n\n <div class=\"callout callout-tip\">\n <span class=\"callout-icon\">Tip<\/span>\n <p>The negative sign in U = \u2212GMm\/r is not optional \u2014 it encodes the bound nature of the system. A satellite in orbit has total energy E = \u2212GMm\/(2r), which is negative, confirming it is gravitationally bound. A positive total energy would mean the object has escaped the gravitational field.<\/p>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">08<\/div>\n <h2 class=\"section-title\">Gravitational Potential and <span>Field Intensity<\/span><\/h2>\n <\/div>\n\n <p>Gravitational potential (V) and gravitational field intensity (E or g-field) are field quantities \u2014 they describe the gravitational environment at a point in space, independent of what test mass is placed there.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Gravitational Potential (V)<\/div>\n <code>V = U\/m = \u2212GM\/r<\/code>\n <code>V is work done per unit mass to bring a test mass from \u221e to point P.<\/code>\n <code>Unit: J\/kg Dimension: [L\u00b2T\u207b\u00b2]<\/code>\n <code>V is always negative (attractive field).<\/code>\n <\/div>\n\n <div class=\"formula-orange\">\n <div class=\"f-label\">Gravitational Field Intensity (I or g-field)<\/div>\n <code>I = F\/m = GM\/r\u00b2 (directed toward the source mass)<\/code>\n <code>Relation: I = \u2212dV\/dr<\/code>\n <code>Unit: N\/kg or m\/s\u00b2 Dimension: [LT\u207b\u00b2]<\/code>\n <\/div>\n\n <p>Inside a uniform spherical shell, the gravitational field is <strong>zero<\/strong> at every point \u2014 the contributions from all parts of the shell cancel out. This is the shell theorem. Outside the shell, the field is identical to that of a point mass at the centre.<\/p>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">09<\/div>\n <h2 class=\"section-title\">Escape <span>Velocity<\/span><\/h2>\n <\/div>\n\n <p>Escape velocity is the minimum initial velocity an object must be given at the surface of a planet so that it can overcome the planet’s gravitational attraction and escape to infinity \u2014 without any further propulsion once launched.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Derivation of Escape Velocity<\/div>\n <code>At launch: KE + PE = 0 (total energy = 0 at escape threshold)<\/code>\n <code>\u00bdmv_e\u00b2 \u2212 GMm\/R = 0<\/code>\n <code>v_e = \u221a(2GM\/R) = \u221a(2gR)<\/code>\n <code>v_e (Earth) = \u221a(2 \u00d7 9.8 \u00d7 6.4 \u00d7 10\u2076) \u2248 11.2 km\/s<\/code>\n <\/div>\n\n <p>Key characteristics of escape velocity:<\/p>\n <ul class=\"content-list\">\n <li>Independent of the mass and direction of the escaping object.<\/li>\n <li>Depends only on the mass (M) and radius (R) of the planet.<\/li>\n <li>v_e = \u221a2 \u00d7 orbital velocity at the surface.<\/li>\n <li>On Moon: v_e \u2248 2.4 km\/s (Moon’s low escape velocity is why it has no atmosphere).<\/li>\n <li>Black holes: escape velocity exceeds the speed of light \u2014 even light cannot escape.<\/li>\n <\/ul>\n\n <div class=\"callout callout-warn\">\n <span class=\"callout-icon\">Warning<\/span>\n <p>Escape velocity is NOT the velocity needed to reach a specific altitude \u2014 it is the velocity to escape to infinity. It is derived by setting total mechanical energy to zero (KE + PE = 0). If total energy remains negative after launch, the object is still gravitationally bound.<\/p>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">10<\/div>\n <h2 class=\"section-title\">Orbital Velocity and <span>Satellites<\/span><\/h2>\n <\/div>\n\n <p>An artificial satellite orbits Earth because the gravitational force provides the necessary centripetal force for circular motion. The velocity at which this balance is achieved is the orbital velocity.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Orbital Velocity Derivation<\/div>\n <code>Gravitational force = Centripetal force<\/code>\n <code>GMm\/(R + h)\u00b2 = mv_o\u00b2\/(R + h)<\/code>\n <code>v_o = \u221a[GM\/(R + h)]<\/code>\n <code>Near surface (h << R): v_o = \u221a(gR) \u2248 7.9 km\/s<\/code>\n <\/div>\n\n <div class=\"formula-orange\">\n <div class=\"f-label\">Time Period of Satellite<\/div>\n <code>T = 2\u03c0(R + h)\/v_o = 2\u03c0\u221a[(R + h)\u00b3\/GM]<\/code>\n <code>Near surface: T \u2248 2\u03c0\u221a(R\/g) \u2248 84 minutes<\/code>\n <code>Note: T\u00b2 \u221d (R + h)\u00b3 \u2014 this is Kepler's third law applied to satellites.<\/code>\n <\/div>\n\n <div class=\"callout callout-tip\">\n <span class=\"callout-icon\">Tip<\/span>\n <p>As orbital radius increases, orbital velocity decreases but time period increases. A satellite at greater height moves slower but takes longer to complete one orbit. These are inverse relationships \u2014 frequently tested in NEET conceptual questions.<\/p>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">11<\/div>\n <h2 class=\"section-title\">Geostationary <span>Satellites<\/span><\/h2>\n <\/div>\n\n <p>A geostationary satellite appears stationary when viewed from Earth because it revolves in the same direction as Earth’s rotation and with exactly the same angular velocity. It is used for communication, weather forecasting, and television broadcasting.<\/p>\n\n <div class=\"formula-orange\">\n <div class=\"f-label\">Conditions for Geostationary Orbit<\/div>\n <code>Time period: T = 24 hours (same as Earth's rotation)<\/code>\n <code>Orbital radius: r \u2248 42,400 km from Earth's centre<\/code>\n <code>Height above surface: h \u2248 36,000 km (\u2248 6R)<\/code>\n <code>Orbit: equatorial plane, west to east direction<\/code>\n <code>Orbital velocity: v_o \u2248 3.1 km\/s<\/code>\n <\/div>\n\n <ul class=\"content-list\">\n <li>The orbit must be in the equatorial plane \u2014 tilted orbits would appear to oscillate north-south over 24 hours.<\/li>\n <li>Direction must be west-to-east (prograde) \u2014 same as Earth’s rotation.<\/li>\n <li>Only one unique altitude satisfies T = 24 h. This makes geostationary orbit slots a finite resource.<\/li>\n <li>GPS satellites are NOT geostationary \u2014 they operate at ~20,200 km altitude in medium Earth orbit (MEO) with periods of ~12 hours.<\/li>\n <\/ul>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">12<\/div>\n <h2 class=\"section-title\">Energy of an <span>Orbiting Satellite<\/span><\/h2>\n <\/div>\n\n <p>For a satellite in circular orbit at radius r = R + h, the energy components are inter-related through the virial theorem for gravitational systems.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Satellite Energy in Circular Orbit<\/div>\n <code>Kinetic energy: KE = +GMm\/(2r) (always positive)<\/code>\n <code>Potential energy: PE = \u2212GMm\/r (always negative)<\/code>\n <code>Total energy: E = \u2212GMm\/(2r) (always negative)<\/code>\n <code>Relation: KE = \u2212E = \u2212PE\/2<\/code>\n <code>|PE| = 2 \u00d7 KE always holds for circular orbits.<\/code>\n <\/div>\n\n <p>The negative total energy confirms the satellite is gravitationally bound. To move a satellite to a higher orbit, energy must be added (total energy increases, becomes less negative). When a satellite loses energy due to atmospheric drag, it spirals inward \u2014 into a lower orbit where its speed is paradoxically higher.<\/p>\n\n <div class=\"callout callout-warn\">\n <span class=\"callout-icon\">Warning<\/span>\n <p>When a satellite moves to a higher orbit, its total energy increases (less negative) but its kinetic energy decreases. This seems counterintuitive \u2014 adding energy makes the satellite move slower. The potential energy gain exceeds the KE loss. This is one of NEET’s favourite conceptual traps in the Gravitation chapter.<\/p>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">13<\/div>\n <h2 class=\"section-title\"><span>Weightlessness<\/span><\/h2>\n <\/div>\n\n <p>Weightlessness is experienced when a body is in free fall \u2014 when the only force acting on it is gravity and there is no supporting normal reaction. Astronauts in an orbiting satellite feel weightless because both the satellite and the astronauts are in the same free-fall state.<\/p>\n\n <div class=\"formula-orange\">\n <div class=\"f-label\">Apparent Weight in Various Situations<\/div>\n <code>Lift accelerating up: W_app = m(g + a) [heavier]<\/code>\n <code>Lift accelerating down: W_app = m(g \u2212 a) [lighter]<\/code>\n <code>Free fall (a = g): W_app = m(g \u2212 g) = 0 [weightless]<\/code>\n <code>Orbiting satellite: Centripetal acc = g at that altitude \u2192 W_app = 0<\/code>\n <\/div>\n\n <p>Gravity still acts on an orbiting astronaut \u2014 in fact, gravity is providing the centripetal force keeping them in orbit. Weightlessness does not mean absence of gravity; it means absence of the contact (normal) force. This distinction is critical for NEET conceptual questions.<\/p>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">14<\/div>\n <h2 class=\"section-title\">Numerical <span>Framework<\/span><\/h2>\n <\/div>\n\n <p>NEET-level numericals in <strong>Gravitation class 11 notes<\/strong> fall into predictable solution patterns. Here is the strategic approach for each type:<\/p>\n\n <div class=\"table-wrap\">\n <table>\n <thead>\n <tr>\n <th>Problem Type<\/th>\n <th>Key Formula<\/th>\n <th>Watch Out For<\/th>\n <\/tr>\n <\/thead>\n <tbody>\n <tr>\n <td>Gravitational force between two bodies<\/td>\n <td>F = Gm\u2081m\u2082\/r\u00b2<\/td>\n <td>Use centre-to-centre distance, not surface distance<\/td>\n <\/tr>\n <tr>\n <td>Value of g at altitude h<\/td>\n <td>g_h = g(1 \u2212 2h\/R) approx<\/td>\n <td>Use exact formula for large h<\/td>\n <\/tr>\n <tr>\n <td>Value of g at depth d<\/td>\n <td>g_d = g(1 \u2212 d\/R)<\/td>\n <td>g = 0 at centre; linear not inverse-square<\/td>\n <\/tr>\n <tr>\n <td>Escape velocity<\/td>\n <td>v_e = \u221a(2gR)<\/td>\n <td>Direction does not matter; no propulsion after launch<\/td>\n <\/tr>\n <tr>\n <td>Orbital velocity at height h<\/td>\n <td>v_o = \u221a[GM\/(R+h)]<\/td>\n <td>Use R + h, not just h<\/td>\n <\/tr>\n <tr>\n <td>Time period of satellite<\/td>\n <td>T = 2\u03c0\u221a[(R+h)\u00b3\/GM]<\/td>\n <td>T\u00b2 \u221d r\u00b3 \u2014 Kepler’s third law applies<\/td>\n <\/tr>\n <tr>\n <td>Satellite energy<\/td>\n <td>E = \u2212GMm\/(2r)<\/td>\n <td>Total energy is negative; KE = |E|, PE = 2E<\/td>\n <\/tr>\n <\/tbody>\n <\/table>\n <\/div>\n\n <div class=\"formula-orange\">\n <div class=\"f-label\">Critical Relationship: v_e vs v_o<\/div>\n <code>v_e = \u221a2 \u00d7 v_o (at the same radius)<\/code>\n <code>v_e (surface) \u2248 11.2 km\/s<\/code>\n <code>v_o (near surface) \u2248 7.9 km\/s<\/code>\n <code>11.2 \/ 7.9 \u2248 \u221a2 \u2713<\/code>\n <\/div>\n\n <div class=\"pdf-btn-wrap\">\n <a href=\"#\" rel=\"nofollow noopener noreferrer\" class=\"pdf-btn\">\n <svg viewBox=\"0 0 24 24\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M19 9h-4V3H9v6H5l7 7 7-7zM5 18v2h14v-2H5z\"\/><\/svg>\n Download These Notes as PDF\n <\/a>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">15<\/div>\n <h2 class=\"section-title\">Conceptual <span>Questions<\/span><\/h2>\n <\/div>\n\n <ul class=\"content-list\">\n <li>The gravitational force between two bodies does not depend on the medium between them \u2014 unlike electrostatic force, which is affected by the permittivity of the medium.<\/li>\n <li>If Earth’s rotation suddenly stopped, g at the equator would increase (the centrifugal reduction of ~0.034 m\/s\u00b2 would be removed), but g at poles would remain unchanged.<\/li>\n <li>A tunnel through Earth’s centre would allow a body to oscillate in simple harmonic motion \u2014 g inside varies linearly, providing restoring force proportional to displacement.<\/li>\n <li>On the Moon, time period of a simple pendulum is longer (T = 2\u03c0\u221a(L\/g), and g_moon = g_earth\/6), but an astronaut’s mass remains the same as on Earth.<\/li>\n <li>Two satellites at different altitudes cannot be in the same orbit \u2014 each altitude has a unique orbital velocity and time period.<\/li>\n <li>The binding energy of a satellite (energy needed to free it from orbit) = GMm\/(2r) = |Total energy|.<\/li>\n <\/ul>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">16<\/div>\n <h2 class=\"section-title\">PYQ <span>Trends<\/span><\/h2>\n <\/div>\n\n <div class=\"table-wrap\">\n <table>\n <thead>\n <tr>\n <th>Topic<\/th>\n <th>Frequency<\/th>\n <th>Type<\/th>\n <\/tr>\n <\/thead>\n <tbody>\n <tr>\n <td><span class=\"pyq-badge\">Very High<\/span>Orbital velocity and satellite energy<\/td>\n <td>2\u20133 questions\/year<\/td>\n <td>Numerical + Conceptual<\/td>\n <\/tr>\n <tr>\n <td><span class=\"pyq-badge\">High<\/span>Escape velocity and v_e vs v_o relation<\/td>\n <td>1\u20132 questions\/year<\/td>\n <td>Conceptual + Numerical<\/td>\n <\/tr>\n <tr>\n <td><span class=\"pyq-badge\">High<\/span>Variation of g (altitude, depth, latitude)<\/td>\n <td>1\u20132 questions\/year<\/td>\n <td>Numerical<\/td>\n <\/tr>\n <tr>\n <td><span class=\"pyq-badge\">Moderate<\/span>Kepler’s third law (T\u00b2 \u221d r\u00b3)<\/td>\n <td>1 question\/year<\/td>\n <td>Numerical<\/td>\n <\/tr>\n <tr>\n <td><span class=\"pyq-badge\">Moderate<\/span>Gravitational potential energy and binding energy<\/td>\n <td>1 question\/year<\/td>\n <td>Numerical<\/td>\n <\/tr>\n <tr>\n <td><span class=\"pyq-badge\">Low<\/span>Weightlessness and geostationary satellites<\/td>\n <td>Occasional<\/td>\n <td>Conceptual<\/td>\n <\/tr>\n <\/tbody>\n <\/table>\n <\/div>\n\n <div class=\"callout callout-tip\">\n <span class=\"callout-icon\">Tip<\/span>\n <p>NEET consistently tests the energy of orbiting satellites \u2014 specifically the relationship KE = \u2212E and PE = 2E. Master the signs and magnitudes of all three energy components (KE, PE, total) and their behaviour as orbital radius changes. This topic appears in nearly every NEET paper.<\/p>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">17<\/div>\n <h2 class=\"section-title\">Chapter <span>Summary<\/span><\/h2>\n <\/div>\n\n <p>Gravitation class 11 notes build a coherent framework from Kepler’s empirical laws through Newton’s universal law to modern satellite applications. Every major formula in the chapter \u2014 g, escape velocity, orbital velocity, satellite energy \u2014 is a direct consequence of F = GMm\/r\u00b2.<\/p>\n\n <div class=\"revision-box\">\n <h3>Quick Revision \u2014 Must-Know Points<\/h3>\n <ul>\n <li>Kepler’s third law: T\u00b2 \u221d r\u00b3; apply as (T\u2081\/T\u2082)\u00b2 = (r\u2081\/r\u2082)\u00b3 for planet comparisons.<\/li>\n <li>Newton’s law: F = Gm\u2081m\u2082\/r\u00b2. Always centre-to-centre distance. Always attractive.<\/li>\n <li>G = 6.674 \u00d7 10\u207b\u00b9\u00b9 N\u00b7m\u00b2\/kg\u00b2. Dimensions: [M\u207b\u00b9L\u00b3T\u207b\u00b2]. Universal constant.<\/li>\n <li>g = GM\/R\u00b2 at Earth’s surface \u2248 9.8 m\/s\u00b2. Independent of mass of falling body.<\/li>\n <li>g decreases with altitude: g_h \u2248 g(1 \u2212 2h\/R). Decreases with depth: g_d = g(1 \u2212 d\/R).<\/li>\n <li>g is maximum at poles and minimum at equator due to Earth’s rotation and oblate shape.<\/li>\n <li>Gravitational PE: U = \u2212GMm\/r. Always negative. Near surface: \u0394U = mgh.<\/li>\n <li>Escape velocity: v_e = \u221a(2gR) \u2248 11.2 km\/s. Independent of mass and direction.<\/li>\n <li>Orbital velocity: v_o = \u221a[GM\/(R+h)] \u2248 7.9 km\/s near surface. v_e = \u221a2 \u00d7 v_o.<\/li>\n <li>Satellite energy: KE = GMm\/2r, PE = \u2212GMm\/r, Total E = \u2212GMm\/2r. E = \u2212KE = PE\/2.<\/li>\n <li>Geostationary: T = 24 h, height \u2248 36,000 km, equatorial, west-to-east orbit.<\/li>\n <li>Weightlessness = free fall state. Gravity acts; normal force = 0.<\/li>\n <\/ul>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">18<\/div>\n <h2 class=\"section-title\">Common <span>Mistakes<\/span><\/h2>\n <\/div>\n\n <ul class=\"content-list\">\n <li><strong>Confusing G and g:<\/strong> G is the universal constant (6.674 \u00d7 10\u207b\u00b9\u00b9); g is the local acceleration (9.8 m\/s\u00b2 at surface). They are related by g = GM\/R\u00b2 but are entirely different quantities.<\/li>\n <li><strong>Using surface g formula at altitude or depth:<\/strong> Once the object is not at Earth’s surface, the formulas change. Use g_h or g_d as applicable \u2014 never plug altitude directly into g = GM\/R\u00b2.<\/li>\n <li><strong>Forgetting the negative sign in U = \u2212GMm\/r:<\/strong> The negative sign is essential. It indicates a bound system. Dropping it completely changes the physics of escape velocity and satellite energy problems.<\/li>\n <li><strong>Using wrong distance in F = Gm\u2081m\u2082\/r\u00b2:<\/strong> r is the centre-to-centre distance, not the surface-to-surface distance. For two spheres of radii R\u2081 and R\u2082 separated by gap d, use r = R\u2081 + R\u2082 + d.<\/li>\n <li><strong>Escape velocity has direction dependency:<\/strong> False. v_e is independent of the launch direction \u2014 a body launched at v_e in any direction (not just vertical) will escape, provided it doesn’t hit Earth first.<\/li>\n <li><strong>Confusing orbital velocity decrease with energy loss:<\/strong> A satellite at a higher orbit moves slower but has higher total energy (less negative). The increase in PE more than compensates for the KE decrease.<\/li>\n <li><strong>Thinking weightlessness means no gravity:<\/strong> Gravity is fully acting on an orbiting astronaut. Weightlessness is the absence of contact force (normal reaction), not absence of gravitational force.<\/li>\n <li><strong>Applying depth formula at surface:<\/strong> At the surface, d = 0, so g_d = g \u2014 this is consistent. At the centre, d = R, so g_d = 0. The formula is linear, not inverse-square inside Earth.<\/li>\n <\/ul>\n<\/div>\n\n\n<div class=\"faq-section\">\n <h2 class=\"faq-title\">Frequently Asked Questions \u2014 <span>Gravitation Class 11<\/span><\/h2>\n\n <details>\n <summary>\n What is the difference between gravitational potential and gravitational potential energy?\n <span class=\"faq-icon\">+<\/span>\n <\/summary>\n <div class=\"faq-body\">\n Gravitational potential energy (U) is the energy of a specific mass m at a point in the gravitational field: U = \u2212GMm\/r. It depends on the test mass m. Gravitational potential (V), on the other hand, is a property of the field itself at that point \u2014 it is the potential energy per unit mass: V = U\/m = \u2212GM\/r. Potential is independent of the test mass and describes the field environment. This distinction is analogous to the difference between electric potential energy and electric potential in electrostatics.\n <\/div>\n <\/details>\n\n <details>\n <summary>\n Why does g decrease both with altitude and with depth?\n <span class=\"faq-icon\">+<\/span>\n <\/summary>\n <div class=\"faq-body\">\n Above the surface, g decreases because the distance from Earth’s centre increases \u2014 the inverse-square law applies (g \u221d 1\/r\u00b2). Below the surface, only the mass enclosed within the sphere of radius (R \u2212 d) contributes to the gravitational force (shell theorem). This enclosed mass decreases as d increases, and decreases faster than the distance decreases, resulting in a net linear decrease in g. At the exact centre, all forces cancel and g = 0.\n <\/div>\n <\/details>\n\n <details>\n <summary>\n How is escape velocity derived, and why is it independent of mass?\n <span class=\"faq-icon\">+<\/span>\n <\/summary>\n <div class=\"faq-body\">\n Escape velocity is derived by setting the total mechanical energy equal to zero \u2014 the minimum condition for escape to infinity. Starting with: \u00bdmv_e\u00b2 \u2212 GMm\/R = 0, solving for v_e gives \u221a(2GM\/R). The mass m of the escaping object cancels out completely in this equation, which is why escape velocity is independent of the escaping object’s mass. It only depends on the mass M and radius R of the planet being escaped from.\n <\/div>\n <\/details>\n\n <details>\n <summary>\n What happens to the orbital speed of a satellite when it moves to a higher orbit?\n <span class=\"faq-icon\">+<\/span>\n <\/summary>\n <div class=\"faq-body\">\n Orbital speed decreases as the satellite moves to a higher orbit. From v_o = \u221a[GM\/(R+h)], as h increases, (R+h) increases, so v_o decreases. However, the time period T increases (T \u221d r^(3\/2)). This seems paradoxical because energy must be added (via rocket thrust) to move to a higher orbit, yet the satellite ends up moving slower. The explanation is that the large increase in gravitational potential energy more than accounts for the decrease in kinetic energy \u2014 total energy increases (becomes less negative).\n <\/div>\n <\/details>\n\n <details>\n <summary>\n Why do astronauts experience weightlessness in a satellite even though gravity is acting on them?\n <span class=\"faq-icon\">+<\/span>\n <\/summary>\n <div class=\"faq-body\">\n Weightlessness is the sensation caused by the absence of a contact (normal) force, not the absence of gravity. In an orbiting satellite, both the satellite and the astronaut are in the same free-fall state \u2014 they are both falling toward Earth at the same rate (the centripetal acceleration equals the local g at that altitude). Because both fall together, the satellite floor never needs to push up against the astronaut. The normal reaction is zero, creating the sensation of weightlessness. Gravity is fully present and is in fact providing the centripetal force for the orbit.\n <\/div>\n <\/details>\n\n <details>\n <summary>\n What is the significance of the negative total energy of a satellite?\n <span class=\"faq-icon\">+<\/span>\n <\/summary>\n <div class=\"faq-body\">\n The negative total energy (E = \u2212GMm\/2r) signifies that the satellite is gravitationally bound to Earth \u2014 it cannot escape without additional energy input. The magnitude of the total energy equals the binding energy: the minimum energy that must be supplied to free the satellite from its orbit and send it to infinity. If total energy were zero, the satellite would be at the escape threshold. If positive, the object would have already escaped. This sign convention is universal for all bound gravitational systems, including planetary orbits.\n <\/div>\n <\/details>\n<\/div>\n\n\n<div class=\"section\" style=\"padding-top:0; border-bottom:none;\">\n <div class=\"related-links\">\n <h4>Recommended Courses and Study Materials<\/h4>\n <ul>\n <li><a href=\"https:\/\/courses.ksquare.co.in\/new-courses\/31-umeed-neet-2026\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">Umeed NEET 2026 Study Materials<\/a><\/li>\n <li><a href=\"https:\/\/courses.ksquare.co.in\/new-courses\/29-pc4-29\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">Grip NCERT Biology<\/a><\/li>\n <li><a href=\"https:\/\/courses.ksquare.co.in\/new-courses\/28-grip-ncert-chemistry\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">Grip NCERT Chemistry<\/a><\/li>\n <\/ul>\n <\/div>\n<\/div>\n\n\n<div class=\"cta-section\">\n <h2>Ready to Score Full Marks in Gravitation?<\/h2>\n <p>Gravitation class 11 notes are complete \u2014 now it is time to practise. Use our NEET rank predictor, join the Mission 180 Physics batch, or download free study materials to push your preparation further.<\/p>\n <div class=\"cta-btns\">\n <a href=\"https:\/\/courses.ksquare.co.in\/new-courses\/3-mission-180-neet-physics-rankers-batch\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" class=\"btn-white\">Join Mission 180 Physics Batch<\/a>\n <a href=\"https:\/\/ksquareinstitute.in\/neet-2026-rank-predictor\/\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" class=\"btn-outline\">Use NEET 2026 Rank Predictor<\/a>\n <a href=\"https:\/\/ksquareinstitute.in\/free-study-material\/\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" class=\"btn-outline\">Download Free Materials<\/a>\n <\/div>\n<\/div>\n\n<\/article>\n<\/body>\n<\/html>\n\n\n\n<!DOCTYPE html>\n<html lang=\"en\">\n<head>\n <meta charset=\"UTF-8\">\n <meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\">\n <title>Table of Contents \u2014 Physics Class 11<\/title>\n \n \n <link rel=\"preconnect\" href=\"https:\/\/fonts.googleapis.com\">\n <link rel=\"preconnect\" href=\"https:\/\/fonts.gstatic.com\" crossorigin>\n <link href=\"https:\/\/fonts.googleapis.com\/css2?family=DM+Sans:ital,opsz,wght@0,9..40,100..1000;1,9..40,100..1000&family=Plus+Jakarta+Sans:ital,wght@0,200..800;1,200..800&display=swap\" rel=\"stylesheet\">\n \n <style>\n \/* Scoped wrapper using a unique ID to prevent CSS conflicts. *\/\n #physics-toc-wrapper {\n font-family: 'DM Sans', sans-serif;\n width: 100%;\n margin: 0;\n padding: 60px 0;\n color: #111;\n background: #fff;\n -webkit-font-smoothing: antialiased;\n }\n\n #physics-toc-wrapper .container-inner {\n width: 100%;\n margin: 0 auto;\n padding: 0; \/* Set left\/right padding to 0 *\/\n }\n\n #physics-toc-wrapper h1 {\n font-family: 'Plus Jakarta Sans', sans-serif;\n font-size: 0.85rem;\n font-weight: 700;\n color: #71717a;\n margin: 0 0 8px;\n letter-spacing: 0.1em;\n text-transform: uppercase;\n padding-left: 16px; \/* Keeping a small offset for headings so they aren't touching the screen edge *\/\n }\n\n #physics-toc-wrapper h2 {\n font-family: 'Plus Jakarta Sans', sans-serif;\n font-size: 2.25rem;\n font-weight: 800;\n margin: 0 0 48px;\n letter-spacing: -0.02em;\n color: #09090b;\n padding-left: 16px; \/* Keeping a small offset for headings *\/\n }\n\n #physics-toc-wrapper table {\n width: 100%;\n border-collapse: collapse;\n border-spacing: 0;\n \/* Border-left and border-right set to none or removed if you want it truly edge-to-edge with the screen *\/\n border-top: 1px solid #e4e4e7;\n border-bottom: 1px solid #e4e4e7;\n }\n\n #physics-toc-wrapper tr {\n border-bottom: 1px solid #e4e4e7;\n transition: all 0.2s ease;\n }\n\n #physics-toc-wrapper tr:hover {\n background-color: #f8fafc;\n }\n\n #physics-toc-wrapper tr:last-child {\n border-bottom: none;\n }\n\n #physics-toc-wrapper td {\n padding: 24px 16px;\n vertical-align: middle;\n font-size: 1.05rem;\n font-weight: 500;\n border-right: 1px solid #e4e4e7;\n }\n\n #physics-toc-wrapper td:last-child {\n border-right: none;\n }\n\n \/* First column (Numbers) alignment and padding *\/\n #physics-toc-wrapper td:first-child {\n color: #a1a1aa;\n font-size: 0.9rem;\n width: 70px;\n font-weight: 400;\n font-variant-numeric: tabular-nums;\n text-align: center;\n padding-left: 10px;\n }\n\n \/* Middle column (Chapter Name) alignment and padding *\/\n #physics-toc-wrapper td:nth-child(2) {\n padding-left: 24px;\n color: #18181b;\n }\n\n \/* Last column (Button) alignment and padding *\/\n #physics-toc-wrapper td:last-child {\n text-align: right;\n width: 180px;\n padding-right: 16px;\n }\n\n \/* Button Styling *\/\n #physics-toc-wrapper a.go {\n display: inline-block;\n font-family: 'Plus Jakarta Sans', sans-serif;\n font-size: 0.75rem;\n font-weight: 800;\n padding: 12px 24px;\n border: 1.5px solid #18181b;\n border-radius: 8px;\n color: #18181b;\n text-decoration: none;\n letter-spacing: 0.05em;\n text-transform: uppercase;\n transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);\n white-space: nowrap;\n }\n\n #physics-toc-wrapper a.go:hover {\n background: #18181b;\n color: #ffffff;\n transform: translateY(-2px);\n box-shadow: 0 4px 12px rgba(24, 24, 27, 0.15);\n }\n\n \/* Responsive adjustments *\/\n @media (max-width: 768px) {\n #physics-toc-wrapper h2 {\n font-size: 1.75rem;\n margin-bottom: 32px;\n }\n #physics-toc-wrapper td {\n padding: 18px 12px;\n font-size: 0.95rem;\n }\n }\n <\/style>\n<\/head>\n<body>\n\n<div id=\"physics-toc-wrapper\">\n <div class=\"container-inner\">\n <h1>Table of Contents<\/h1>\n <h2>Physics — Class 11<\/h2>\n \n <table>\n <tr><td>01<\/td><td>Units and Measurements<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/units-and-measurements-class-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>02<\/td><td>Motion in a Straight Line<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/motion-in-a-straight-line-class-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>03<\/td><td>Motion in a Plane<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/motion-in-a-plane-class-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>04<\/td><td>Laws of Motion<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/laws-of-motion-class-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>05<\/td><td>Work, Energy and Power<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/work-energy-and-power-class-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>06<\/td><td>System of Particles and Rotational Motion<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/system-of-particles-and-rotational-motion-class-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>07<\/td><td>Gravitation<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/gravitation-class-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>08<\/td><td>Mechanical Properties of Solids<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/mechanical-properties-of-solids-class-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>09<\/td><td>Mechanical Properties of Fluids<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/mechanical-properties-of-fluids-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>10<\/td><td>Thermal Properties of Matter<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/thermal-properties-of-matter-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>11<\/td><td>Thermodynamics<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/thermodynamics-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>12<\/td><td>Kinetic Theory<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/kinetic-theory-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>13<\/td><td>Oscillations<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/oscillations-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>14<\/td><td>Waves<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/waves-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <\/table>\n <\/div>\n<\/div>\n\n<\/body>\n<\/html>\n","protected":false},"excerpt":{"rendered":"<p>Gravitation Class 11 Notes | NEET Physics Complete Guide 01 Introduction to Gravitation These Gravitation class 11 notes cover one of the most conceptually rich and NEET-relevant chapters in Class 11 Physics. Gravitation is the universal force of attraction that acts between every two objects possessing mass. It governs why an apple falls to the […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[127],"tags":[],"class_list":["post-3943","post","type-post","status-publish","format-standard","hentry","category-free-study-material"],"blocksy_meta":{"page_structure_type":"type-1","styles_descriptor":{"styles":{"desktop":"","tablet":"","mobile":""},"google_fonts":[],"version":6}},"_links":{"self":[{"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/posts\/3943","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/comments?post=3943"}],"version-history":[{"count":2,"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/posts\/3943\/revisions"}],"predecessor-version":[{"id":4210,"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/posts\/3943\/revisions\/4210"}],"wp:attachment":[{"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/media?parent=3943"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/categories?post=3943"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/tags?post=3943"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}

{"id":3943,"date":"2026-03-27T08:19:15","date_gmt":"2026-03-27T08:19:15","guid":{"rendered":"https:\/\/ksquareinstitute.in\/blog\/?p=3943"},"modified":"2026-04-03T12:15:53","modified_gmt":"2026-04-03T12:15:53","slug":"gravitation-class-11-notes","status":"publish","type":"post","link":"https:\/\/ksquareinstitute.in\/blog\/gravitation-class-11-notes\/","title":{"rendered":"Gravitation Class 11 Notes: Complete Theory, Formulas, Numericals & PYQs"},"content":{"rendered":"\n\n\n\n\n\nGravitation Class 11 Notes | NEET Physics Complete Guide<\/title>\n<meta name=\"description\" content=\"Complete Gravitation class 11 notes for NEET Physics. Covers Kepler's laws, Newton's law, escape velocity, orbital velocity, satellites, and variation of g with formulas and PYQs.\">\n<link rel=\"preconnect\" href=\"https:\/\/fonts.googleapis.com\">\n<link rel=\"preconnect\" href=\"https:\/\/fonts.gstatic.com\" crossorigin>\n<link href=\"https:\/\/fonts.googleapis.com\/css2?family=Plus+Jakarta+Sans:wght@400;500;600;700;800&family=DM+Sans:ital,wght@0,300;0,400;0,500;0,600;1,400&family=JetBrains+Mono:wght@400;500;600&display=swap\" rel=\"stylesheet\">\n<style>\n *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }\n\n :root {\n --accent: #e8600a;\n --accent-light: #fff3ec;\n --accent-mid: #ffd9bf;\n --dark: #111827;\n --text: #1a1a1a;\n --text-muted: #555;\n --border: #e5e7eb;\n --tip-bg: #eff6ff;\n --tip-border: #3b82f6;\n --warn-bg: #fff3ec;\n --warn-border: #e8600a;\n --green-bg: #f0fdf4;\n --green-border: #22c55e;\n --green-text: #166534;\n }\n\n body {\n font-family: 'DM Sans', sans-serif;\n color: var(--text);\n background: #fff;\n font-size: 16px;\n line-height: 1.75;\n margin: 0;\n padding: 0;\n }\n\n article {\n width: 100%;\n padding: 0;\n margin: 0;\n }\n\n \/* \u2500\u2500 SECTION \u2500\u2500 *\/\n .section {\n padding: 52px 0;\n margin: 0;\n border-bottom: 1px solid var(--border);\n }\n .section:last-of-type { border-bottom: none; 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margin: 0; color: #7c2d12; }\n\n \/* \u2500\u2500 CONTENT LIST \u2500\u2500 *\/\n ul.content-list {\n padding-left: 0;\n list-style: none;\n margin: 14px 0;\n display: grid;\n gap: 8px;\n }\n ul.content-list li {\n padding-left: 22px;\n position: relative;\n font-size: 15px;\n }\n ul.content-list li::before {\n content: '';\n position: absolute;\n left: 0; top: 9px;\n width: 8px; height: 8px;\n background: var(--accent);\n border-radius: 50%;\n }\n\n \/* \u2500\u2500 TWO COLUMN \u2500\u2500 *\/\n .two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; margin: 20px 0; }\n @media (max-width: 640px) { .two-col { grid-template-columns: 1fr; } .cta-section { padding: 48px 0; } }\n\n a { color: var(--accent); }\n strong { font-weight: 600; }\n\n .pyq-badge {\n display: inline-block;\n background: #fef3c7;\n border: 1px solid #fbbf24;\n color: #92400e;\n font-size: 11px;\n font-weight: 700;\n padding: 2px 8px;\n border-radius: 4px;\n font-family: 'Plus Jakarta Sans', sans-serif;\n letter-spacing: 0.5px;\n text-transform: uppercase;\n margin-right: 8px;\n }\n<\/style>\n<\/head>\n<body>\n<article>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">01<\/div>\n <h2 class=\"section-title\">Introduction to <span>Gravitation<\/span><\/h2>\n <\/div>\n\n <p>These <strong>Gravitation class 11 notes<\/strong> cover one of the most conceptually rich and NEET-relevant chapters in Class 11 Physics. Gravitation is the universal force of attraction that acts between every two objects possessing mass. It governs why an apple falls to the ground, why the Moon orbits Earth, why planets trace elliptical paths around the Sun, and how satellites remain in orbit. Unlike contact forces, gravitation acts across empty space over unlimited distances \u2014 making it the dominant force at cosmic scales.<\/p>\n\n <p>The chapter progresses from Kepler’s observational laws through Newton’s quantitative formulation, to modern applications in satellite technology. Every concept introduced here has direct NEET application, and the formulas are closely inter-linked \u2014 escape velocity, orbital velocity, gravitational potential energy, and g-variation all derive from Newton’s single law of gravitation.<\/p>\n\n <div class=\"highlight-grid\">\n <div class=\"highlight-card\">\n <div class=\"hc-title\">Chapter Scope<\/div>\n <p>From falling bodies on Earth to orbiting satellites and planetary motion.<\/p>\n <\/div>\n <div class=\"highlight-card\">\n <div class=\"hc-title\">NEET Weightage<\/div>\n <p>2\u20134 questions per year. Consistent, high-scoring chapter for prepared students.<\/p>\n <\/div>\n <div class=\"highlight-card\">\n <div class=\"hc-title\">Key Concept<\/div>\n <p>One universal law \u2014 Newton’s law \u2014 generates all other formulas in this chapter.<\/p>\n <\/div>\n <\/div>\n\n <div class=\"related-links\">\n <h4>Related Resources<\/h4>\n <ul>\n <li><a href=\"https:\/\/ksquareinstitute.in\/blog\/neet-physics-survival-kit-2026\/\">NEET Physics Survival Kit<\/a><\/li>\n <li><a href=\"https:\/\/ksquareinstitute.in\/blog\/organic-chemistry-strategy-neet\/\">Organic Chemistry Strategy<\/a><\/li>\n <li><a href=\"https:\/\/ksquareinstitute.in\/blog\/neet-biology-tricks-for-exams\/\">NEET Biology Tricks for Exams<\/a><\/li>\n <li><a href=\"https:\/\/ksquareinstitute.in\/blog\/score-340-in-neet-biology\/\">How to Score 340+ in NEET Biology<\/a><\/li>\n <li><a href=\"https:\/\/ksquareinstitute.in\/blog\/top-10-tricky-neet-biology-diagrams\/\">Top 10 Tricky NEET Biology Diagrams<\/a><\/li>\n <li><a href=\"https:\/\/ksquareinstitute.in\/free-study-material\/\">Free Study Materials<\/a><\/li>\n <\/ul>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">02<\/div>\n <h2 class=\"section-title\">Kepler’s Laws of <span>Planetary Motion<\/span><\/h2>\n <\/div>\n\n <p>Before Newton derived his law analytically, Johannes Kepler established three empirical laws by meticulously analyzing Tycho Brahe’s observational data on planetary positions. These laws describe the geometry and timing of planetary orbits with precision.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Kepler’s Three Laws<\/div>\n <code>Law 1 (Orbits): All planets move in elliptical orbits with the Sun at one focus.<\/code>\n <code>Law 2 (Areas): A line joining a planet to the Sun sweeps equal areas in equal times.<\/code>\n <code>Law 3 (Periods): T\u00b2 \u221d r\u00b3 \u27f9 T\u00b2\/r\u00b3 = constant for all planets<\/code>\n <\/div>\n\n <p><strong>Law 2 (equal areas)<\/strong> is a direct consequence of conservation of angular momentum \u2014 no external torque acts on the planet-Sun system, so L = mvr is conserved. When the planet is closer (perihelion), r is small, so v must be large. When farther (aphelion), v is smaller.<\/p>\n\n <p><strong>Law 3<\/strong> is the most quantitatively useful for NEET. It allows comparison of orbital periods and radii: if Earth’s period is 1 year at 1 AU, Jupiter’s period can be calculated from its orbital radius alone.<\/p>\n\n <div class=\"callout callout-tip\">\n <span class=\"callout-icon\">Tip<\/span>\n <p>For NEET, Kepler’s third law T\u00b2 \u221d r\u00b3 is tested by giving two planets’ orbital radii and asking for the ratio of their time periods. Apply (T\u2081\/T\u2082)\u00b2 = (r\u2081\/r\u2082)\u00b3 directly.<\/p>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">03<\/div>\n <h2 class=\"section-title\">Newton’s Law of <span>Universal Gravitation<\/span><\/h2>\n <\/div>\n\n <p>Newton unified terrestrial and celestial mechanics with a single quantitative statement: <strong>every particle in the universe attracts every other particle with a force proportional to the product of their masses and inversely proportional to the square of the distance between them.<\/strong> The force acts along the line joining their centres.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Newton’s Law of Gravitation<\/div>\n <code>F = G \u00d7 m\u2081 \u00d7 m\u2082 \/ r\u00b2<\/code>\n <code>F = gravitational force (N)<\/code>\n <code>G = 6.674 \u00d7 10\u207b\u00b9\u00b9 N\u00b7m\u00b2\/kg\u00b2 (gravitational constant)<\/code>\n <code>m\u2081, m\u2082 = masses of the two bodies (kg)<\/code>\n <code>r = distance between their centres (m)<\/code>\n <\/div>\n\n <p>Key properties of gravitational force:<\/p>\n <ul class=\"content-list\">\n <li>Always attractive \u2014 never repulsive between masses.<\/li>\n <li>Acts along the line joining the two bodies (central force).<\/li>\n <li>Obeys Newton’s third law: F\u2081\u2082 = \u2212F\u2082\u2081 (equal in magnitude, opposite in direction).<\/li>\n <li>Independent of the medium between the two bodies.<\/li>\n <li>Follows superposition: total force on a body is the vector sum of individual gravitational forces from all other bodies.<\/li>\n <\/ul>\n\n <div class=\"callout callout-warn\">\n <span class=\"callout-icon\">Warning<\/span>\n <p>Newton’s law applies to point masses or uniform spheres. For a uniform sphere, the entire mass can be assumed concentrated at the centre \u2014 valid only outside the sphere. Inside a uniform sphere, only the mass enclosed within the radius contributes to the force.<\/p>\n <\/div>\n<\/div>\n\n\n<a href=\"https:\/\/courses.ksquare.co.in\/new-courses\/3-mission-180-neet-physics-rankers-batch\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" style=\"display:block; margin-bottom:20px;\">\n <img decoding=\"async\" src=\"https:\/\/ksquareinstitute.in\/blog\/wp-content\/uploads\/2026\/03\/Course-Poromo-Banner-scaled.png\" alt=\"Mission 180 NEET Physics Rankers Batch - KSquare Career Institute\" style=\"width:100%; height:auto; border-radius:10px; display:block;\">\n<\/a>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">04<\/div>\n <h2 class=\"section-title\">Gravitational Constant <span>(G)<\/span><\/h2>\n <\/div>\n\n <p>The gravitational constant G is a fundamental physical constant that quantifies the strength of the gravitational interaction. Its value is extraordinarily small, which is why gravitational forces between everyday objects are negligible \u2014 only astronomical masses make gravity perceptible.<\/p>\n\n <div class=\"formula-orange\">\n <div class=\"f-label\">Value and Dimensions of G<\/div>\n <code>G = 6.674 \u00d7 10\u207b\u00b9\u00b9 N\u00b7m\u00b2\u00b7kg\u207b\u00b2<\/code>\n <code>Dimensional formula: [M\u207b\u00b9 L\u00b3 T\u207b\u00b2]<\/code>\n <code>G is a scalar quantity; same value throughout the universe.<\/code>\n <\/div>\n\n <p>G was first measured experimentally by Henry Cavendish in 1798 using a torsion balance apparatus (the Cavendish experiment). Two small lead spheres were attracted to two large lead spheres, and the tiny twist in the suspension wire allowed G to be calculated. G does not vary with temperature, pressure, medium, or location \u2014 it is a true universal constant.<\/p>\n\n <div class=\"callout callout-tip\">\n <span class=\"callout-icon\">Tip<\/span>\n <p>Do not confuse G (universal gravitational constant, 6.674 \u00d7 10\u207b\u00b9\u00b9) with g (acceleration due to gravity, ~9.8 m\/s\u00b2). G is universal and constant; g varies with location and is derived from G, M, and R of the planet.<\/p>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">05<\/div>\n <h2 class=\"section-title\">Acceleration Due to <span>Gravity (g)<\/span><\/h2>\n <\/div>\n\n <p>When an object is in free fall near Earth’s surface, it accelerates at a rate determined by Earth’s gravitational pull. This acceleration, called <strong>g<\/strong>, is derived by equating Newton’s gravitational force to Newton’s second law of motion.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Derivation of g<\/div>\n <code>Gravitational force: F = GMm\/R\u00b2<\/code>\n <code>Newton's 2nd law: F = mg<\/code>\n <code>Therefore: g = GM\/R\u00b2<\/code>\n <code>g_Earth \u2248 9.8 m\/s\u00b2 (standard value at surface)<\/code>\n <code>M = mass of Earth = 6 \u00d7 10\u00b2\u2074 kg<\/code>\n <code>R = radius of Earth = 6.4 \u00d7 10\u2076 m<\/code>\n <\/div>\n\n <p>Note that g is independent of the mass of the falling body \u2014 all objects regardless of mass fall with the same acceleration in a vacuum. This is the equivalence principle, foundational to Einstein’s General Theory of Relativity.<\/p>\n\n <div class=\"callout callout-warn\">\n <span class=\"callout-icon\">Warning<\/span>\n <p>The formula g = GM\/R\u00b2 gives the surface value of g. At altitude h or depth d, the formula changes. Never use the surface formula when the problem specifies a location above or below Earth’s surface.<\/p>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">06<\/div>\n <h2 class=\"section-title\">Variation of g \u2014 Altitude, Depth, <span>and Latitude<\/span><\/h2>\n <\/div>\n\n <p>The value of <strong>g<\/strong> is not constant \u2014 it varies with position on or above Earth. Understanding these variations is critical for <strong>Gravitation class 11 notes<\/strong> and appears frequently in NEET numericals.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Variation with Altitude (h above surface)<\/div>\n <code>g_h = g(1 \u2212 2h\/R) for h << R (approximate)<\/code>\n <code>g_h = GM\/(R + h)\u00b2 (exact formula)<\/code>\n <code>g decreases with increasing altitude.<\/code>\n <\/div>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Variation with Depth (d below surface)<\/div>\n <code>g_d = g(1 \u2212 d\/R)<\/code>\n <code>At the centre of Earth (d = R): g_d = 0<\/code>\n <code>g decreases linearly with depth inside Earth.<\/code>\n <\/div>\n\n <div class=\"formula-orange\">\n <div class=\"f-label\">Variation with Latitude (\u03c6)<\/div>\n <code>g_\u03c6 = g \u2212 R\u03c9\u00b2cos\u00b2\u03c6<\/code>\n <code>g is maximum at poles (\u03c6 = 90\u00b0, cos \u03c6 = 0)<\/code>\n <code>g is minimum at equator (\u03c6 = 0\u00b0, cos \u03c6 = 1)<\/code>\n <code>\u03c9 = angular velocity of Earth's rotation<\/code>\n <\/div>\n\n <div class=\"table-wrap\">\n <table>\n <thead>\n <tr>\n <th>Factor<\/th>\n <th>Effect on g<\/th>\n <th>Rate of Change<\/th>\n <\/tr>\n <\/thead>\n <tbody>\n <tr>\n <td>Altitude (h above surface)<\/td>\n <td>Decreases<\/td>\n <td>Inversely with (R + h)\u00b2<\/td>\n <\/tr>\n <tr>\n <td>Depth (d below surface)<\/td>\n <td>Decreases linearly<\/td>\n <td>g_d = g(1 \u2212 d\/R)<\/td>\n <\/tr>\n <tr>\n <td>Latitude (towards poles)<\/td>\n <td>Increases<\/td>\n <td>g_pole > g_equator by ~0.05 m\/s\u00b2<\/td>\n <\/tr>\n <tr>\n <td>Rotation of Earth<\/td>\n <td>Reduces effective g<\/td>\n <td>Effect maximum at equator<\/td>\n <\/tr>\n <\/tbody>\n <\/table>\n <\/div>\n\n <div class=\"callout callout-warn\">\n <span class=\"callout-icon\">Warning<\/span>\n <p>A classic NEET trap: g at height h equals g at depth d does NOT mean h = d. The altitude formula has a squared term (exact) or a factor of 2 (approximate), while the depth formula is linear. For the approximate case: g(1 \u2212 2h\/R) = g(1 \u2212 d\/R) gives d = 2h.<\/p>\n <\/div>\n<\/div>\n\n\n<a href=\"https:\/\/ksquareinstitute.in\/neet-2026-rank-predictor\/\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" style=\"display:block; margin-bottom:20px;\">\n <img decoding=\"async\" src=\"https:\/\/ksquareinstitute.in\/blog\/wp-content\/uploads\/2026\/03\/neet-2026-college-and-rank-predictor-scaled.png\" alt=\"NEET 2026 College and Rank Predictor - KSquare Career Institute\" style=\"width:100%; height:auto; border-radius:10px; display:block;\">\n<\/a>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">07<\/div>\n <h2 class=\"section-title\">Gravitational <span>Potential Energy<\/span><\/h2>\n <\/div>\n\n <p>Gravitational potential energy (U) is the work done by an external agent in moving a mass from infinity to a given point in the gravitational field, without any change in kinetic energy. Because gravity is attractive and does positive work as the mass approaches, the external agent does negative work \u2014 hence U is always negative for gravitational systems.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Gravitational Potential Energy<\/div>\n <code>U = \u2212GMm\/r<\/code>\n <code>U \u2192 0 as r \u2192 \u221e (reference point at infinity)<\/code>\n <code>Near Earth's surface: U = mgh (for small h, approximate)<\/code>\n <code>Change in PE: \u0394U = mgh (valid only near surface where g is constant)<\/code>\n <\/div>\n\n <div class=\"callout callout-tip\">\n <span class=\"callout-icon\">Tip<\/span>\n <p>The negative sign in U = \u2212GMm\/r is not optional \u2014 it encodes the bound nature of the system. A satellite in orbit has total energy E = \u2212GMm\/(2r), which is negative, confirming it is gravitationally bound. A positive total energy would mean the object has escaped the gravitational field.<\/p>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">08<\/div>\n <h2 class=\"section-title\">Gravitational Potential and <span>Field Intensity<\/span><\/h2>\n <\/div>\n\n <p>Gravitational potential (V) and gravitational field intensity (E or g-field) are field quantities \u2014 they describe the gravitational environment at a point in space, independent of what test mass is placed there.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Gravitational Potential (V)<\/div>\n <code>V = U\/m = \u2212GM\/r<\/code>\n <code>V is work done per unit mass to bring a test mass from \u221e to point P.<\/code>\n <code>Unit: J\/kg Dimension: [L\u00b2T\u207b\u00b2]<\/code>\n <code>V is always negative (attractive field).<\/code>\n <\/div>\n\n <div class=\"formula-orange\">\n <div class=\"f-label\">Gravitational Field Intensity (I or g-field)<\/div>\n <code>I = F\/m = GM\/r\u00b2 (directed toward the source mass)<\/code>\n <code>Relation: I = \u2212dV\/dr<\/code>\n <code>Unit: N\/kg or m\/s\u00b2 Dimension: [LT\u207b\u00b2]<\/code>\n <\/div>\n\n <p>Inside a uniform spherical shell, the gravitational field is <strong>zero<\/strong> at every point \u2014 the contributions from all parts of the shell cancel out. This is the shell theorem. Outside the shell, the field is identical to that of a point mass at the centre.<\/p>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">09<\/div>\n <h2 class=\"section-title\">Escape <span>Velocity<\/span><\/h2>\n <\/div>\n\n <p>Escape velocity is the minimum initial velocity an object must be given at the surface of a planet so that it can overcome the planet’s gravitational attraction and escape to infinity \u2014 without any further propulsion once launched.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Derivation of Escape Velocity<\/div>\n <code>At launch: KE + PE = 0 (total energy = 0 at escape threshold)<\/code>\n <code>\u00bdmv_e\u00b2 \u2212 GMm\/R = 0<\/code>\n <code>v_e = \u221a(2GM\/R) = \u221a(2gR)<\/code>\n <code>v_e (Earth) = \u221a(2 \u00d7 9.8 \u00d7 6.4 \u00d7 10\u2076) \u2248 11.2 km\/s<\/code>\n <\/div>\n\n <p>Key characteristics of escape velocity:<\/p>\n <ul class=\"content-list\">\n <li>Independent of the mass and direction of the escaping object.<\/li>\n <li>Depends only on the mass (M) and radius (R) of the planet.<\/li>\n <li>v_e = \u221a2 \u00d7 orbital velocity at the surface.<\/li>\n <li>On Moon: v_e \u2248 2.4 km\/s (Moon’s low escape velocity is why it has no atmosphere).<\/li>\n <li>Black holes: escape velocity exceeds the speed of light \u2014 even light cannot escape.<\/li>\n <\/ul>\n\n <div class=\"callout callout-warn\">\n <span class=\"callout-icon\">Warning<\/span>\n <p>Escape velocity is NOT the velocity needed to reach a specific altitude \u2014 it is the velocity to escape to infinity. It is derived by setting total mechanical energy to zero (KE + PE = 0). If total energy remains negative after launch, the object is still gravitationally bound.<\/p>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">10<\/div>\n <h2 class=\"section-title\">Orbital Velocity and <span>Satellites<\/span><\/h2>\n <\/div>\n\n <p>An artificial satellite orbits Earth because the gravitational force provides the necessary centripetal force for circular motion. The velocity at which this balance is achieved is the orbital velocity.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Orbital Velocity Derivation<\/div>\n <code>Gravitational force = Centripetal force<\/code>\n <code>GMm\/(R + h)\u00b2 = mv_o\u00b2\/(R + h)<\/code>\n <code>v_o = \u221a[GM\/(R + h)]<\/code>\n <code>Near surface (h << R): v_o = \u221a(gR) \u2248 7.9 km\/s<\/code>\n <\/div>\n\n <div class=\"formula-orange\">\n <div class=\"f-label\">Time Period of Satellite<\/div>\n <code>T = 2\u03c0(R + h)\/v_o = 2\u03c0\u221a[(R + h)\u00b3\/GM]<\/code>\n <code>Near surface: T \u2248 2\u03c0\u221a(R\/g) \u2248 84 minutes<\/code>\n <code>Note: T\u00b2 \u221d (R + h)\u00b3 \u2014 this is Kepler's third law applied to satellites.<\/code>\n <\/div>\n\n <div class=\"callout callout-tip\">\n <span class=\"callout-icon\">Tip<\/span>\n <p>As orbital radius increases, orbital velocity decreases but time period increases. A satellite at greater height moves slower but takes longer to complete one orbit. These are inverse relationships \u2014 frequently tested in NEET conceptual questions.<\/p>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">11<\/div>\n <h2 class=\"section-title\">Geostationary <span>Satellites<\/span><\/h2>\n <\/div>\n\n <p>A geostationary satellite appears stationary when viewed from Earth because it revolves in the same direction as Earth’s rotation and with exactly the same angular velocity. It is used for communication, weather forecasting, and television broadcasting.<\/p>\n\n <div class=\"formula-orange\">\n <div class=\"f-label\">Conditions for Geostationary Orbit<\/div>\n <code>Time period: T = 24 hours (same as Earth's rotation)<\/code>\n <code>Orbital radius: r \u2248 42,400 km from Earth's centre<\/code>\n <code>Height above surface: h \u2248 36,000 km (\u2248 6R)<\/code>\n <code>Orbit: equatorial plane, west to east direction<\/code>\n <code>Orbital velocity: v_o \u2248 3.1 km\/s<\/code>\n <\/div>\n\n <ul class=\"content-list\">\n <li>The orbit must be in the equatorial plane \u2014 tilted orbits would appear to oscillate north-south over 24 hours.<\/li>\n <li>Direction must be west-to-east (prograde) \u2014 same as Earth’s rotation.<\/li>\n <li>Only one unique altitude satisfies T = 24 h. This makes geostationary orbit slots a finite resource.<\/li>\n <li>GPS satellites are NOT geostationary \u2014 they operate at ~20,200 km altitude in medium Earth orbit (MEO) with periods of ~12 hours.<\/li>\n <\/ul>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">12<\/div>\n <h2 class=\"section-title\">Energy of an <span>Orbiting Satellite<\/span><\/h2>\n <\/div>\n\n <p>For a satellite in circular orbit at radius r = R + h, the energy components are inter-related through the virial theorem for gravitational systems.<\/p>\n\n <div class=\"formula-dark\">\n <div class=\"f-label\">Satellite Energy in Circular Orbit<\/div>\n <code>Kinetic energy: KE = +GMm\/(2r) (always positive)<\/code>\n <code>Potential energy: PE = \u2212GMm\/r (always negative)<\/code>\n <code>Total energy: E = \u2212GMm\/(2r) (always negative)<\/code>\n <code>Relation: KE = \u2212E = \u2212PE\/2<\/code>\n <code>|PE| = 2 \u00d7 KE always holds for circular orbits.<\/code>\n <\/div>\n\n <p>The negative total energy confirms the satellite is gravitationally bound. To move a satellite to a higher orbit, energy must be added (total energy increases, becomes less negative). When a satellite loses energy due to atmospheric drag, it spirals inward \u2014 into a lower orbit where its speed is paradoxically higher.<\/p>\n\n <div class=\"callout callout-warn\">\n <span class=\"callout-icon\">Warning<\/span>\n <p>When a satellite moves to a higher orbit, its total energy increases (less negative) but its kinetic energy decreases. This seems counterintuitive \u2014 adding energy makes the satellite move slower. The potential energy gain exceeds the KE loss. This is one of NEET’s favourite conceptual traps in the Gravitation chapter.<\/p>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">13<\/div>\n <h2 class=\"section-title\"><span>Weightlessness<\/span><\/h2>\n <\/div>\n\n <p>Weightlessness is experienced when a body is in free fall \u2014 when the only force acting on it is gravity and there is no supporting normal reaction. Astronauts in an orbiting satellite feel weightless because both the satellite and the astronauts are in the same free-fall state.<\/p>\n\n <div class=\"formula-orange\">\n <div class=\"f-label\">Apparent Weight in Various Situations<\/div>\n <code>Lift accelerating up: W_app = m(g + a) [heavier]<\/code>\n <code>Lift accelerating down: W_app = m(g \u2212 a) [lighter]<\/code>\n <code>Free fall (a = g): W_app = m(g \u2212 g) = 0 [weightless]<\/code>\n <code>Orbiting satellite: Centripetal acc = g at that altitude \u2192 W_app = 0<\/code>\n <\/div>\n\n <p>Gravity still acts on an orbiting astronaut \u2014 in fact, gravity is providing the centripetal force keeping them in orbit. Weightlessness does not mean absence of gravity; it means absence of the contact (normal) force. This distinction is critical for NEET conceptual questions.<\/p>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">14<\/div>\n <h2 class=\"section-title\">Numerical <span>Framework<\/span><\/h2>\n <\/div>\n\n <p>NEET-level numericals in <strong>Gravitation class 11 notes<\/strong> fall into predictable solution patterns. Here is the strategic approach for each type:<\/p>\n\n <div class=\"table-wrap\">\n <table>\n <thead>\n <tr>\n <th>Problem Type<\/th>\n <th>Key Formula<\/th>\n <th>Watch Out For<\/th>\n <\/tr>\n <\/thead>\n <tbody>\n <tr>\n <td>Gravitational force between two bodies<\/td>\n <td>F = Gm\u2081m\u2082\/r\u00b2<\/td>\n <td>Use centre-to-centre distance, not surface distance<\/td>\n <\/tr>\n <tr>\n <td>Value of g at altitude h<\/td>\n <td>g_h = g(1 \u2212 2h\/R) approx<\/td>\n <td>Use exact formula for large h<\/td>\n <\/tr>\n <tr>\n <td>Value of g at depth d<\/td>\n <td>g_d = g(1 \u2212 d\/R)<\/td>\n <td>g = 0 at centre; linear not inverse-square<\/td>\n <\/tr>\n <tr>\n <td>Escape velocity<\/td>\n <td>v_e = \u221a(2gR)<\/td>\n <td>Direction does not matter; no propulsion after launch<\/td>\n <\/tr>\n <tr>\n <td>Orbital velocity at height h<\/td>\n <td>v_o = \u221a[GM\/(R+h)]<\/td>\n <td>Use R + h, not just h<\/td>\n <\/tr>\n <tr>\n <td>Time period of satellite<\/td>\n <td>T = 2\u03c0\u221a[(R+h)\u00b3\/GM]<\/td>\n <td>T\u00b2 \u221d r\u00b3 \u2014 Kepler’s third law applies<\/td>\n <\/tr>\n <tr>\n <td>Satellite energy<\/td>\n <td>E = \u2212GMm\/(2r)<\/td>\n <td>Total energy is negative; KE = |E|, PE = 2E<\/td>\n <\/tr>\n <\/tbody>\n <\/table>\n <\/div>\n\n <div class=\"formula-orange\">\n <div class=\"f-label\">Critical Relationship: v_e vs v_o<\/div>\n <code>v_e = \u221a2 \u00d7 v_o (at the same radius)<\/code>\n <code>v_e (surface) \u2248 11.2 km\/s<\/code>\n <code>v_o (near surface) \u2248 7.9 km\/s<\/code>\n <code>11.2 \/ 7.9 \u2248 \u221a2 \u2713<\/code>\n <\/div>\n\n <div class=\"pdf-btn-wrap\">\n <a href=\"#\" rel=\"nofollow noopener noreferrer\" class=\"pdf-btn\">\n <svg viewBox=\"0 0 24 24\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M19 9h-4V3H9v6H5l7 7 7-7zM5 18v2h14v-2H5z\"\/><\/svg>\n Download These Notes as PDF\n <\/a>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">15<\/div>\n <h2 class=\"section-title\">Conceptual <span>Questions<\/span><\/h2>\n <\/div>\n\n <ul class=\"content-list\">\n <li>The gravitational force between two bodies does not depend on the medium between them \u2014 unlike electrostatic force, which is affected by the permittivity of the medium.<\/li>\n <li>If Earth’s rotation suddenly stopped, g at the equator would increase (the centrifugal reduction of ~0.034 m\/s\u00b2 would be removed), but g at poles would remain unchanged.<\/li>\n <li>A tunnel through Earth’s centre would allow a body to oscillate in simple harmonic motion \u2014 g inside varies linearly, providing restoring force proportional to displacement.<\/li>\n <li>On the Moon, time period of a simple pendulum is longer (T = 2\u03c0\u221a(L\/g), and g_moon = g_earth\/6), but an astronaut’s mass remains the same as on Earth.<\/li>\n <li>Two satellites at different altitudes cannot be in the same orbit \u2014 each altitude has a unique orbital velocity and time period.<\/li>\n <li>The binding energy of a satellite (energy needed to free it from orbit) = GMm\/(2r) = |Total energy|.<\/li>\n <\/ul>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">16<\/div>\n <h2 class=\"section-title\">PYQ <span>Trends<\/span><\/h2>\n <\/div>\n\n <div class=\"table-wrap\">\n <table>\n <thead>\n <tr>\n <th>Topic<\/th>\n <th>Frequency<\/th>\n <th>Type<\/th>\n <\/tr>\n <\/thead>\n <tbody>\n <tr>\n <td><span class=\"pyq-badge\">Very High<\/span>Orbital velocity and satellite energy<\/td>\n <td>2\u20133 questions\/year<\/td>\n <td>Numerical + Conceptual<\/td>\n <\/tr>\n <tr>\n <td><span class=\"pyq-badge\">High<\/span>Escape velocity and v_e vs v_o relation<\/td>\n <td>1\u20132 questions\/year<\/td>\n <td>Conceptual + Numerical<\/td>\n <\/tr>\n <tr>\n <td><span class=\"pyq-badge\">High<\/span>Variation of g (altitude, depth, latitude)<\/td>\n <td>1\u20132 questions\/year<\/td>\n <td>Numerical<\/td>\n <\/tr>\n <tr>\n <td><span class=\"pyq-badge\">Moderate<\/span>Kepler’s third law (T\u00b2 \u221d r\u00b3)<\/td>\n <td>1 question\/year<\/td>\n <td>Numerical<\/td>\n <\/tr>\n <tr>\n <td><span class=\"pyq-badge\">Moderate<\/span>Gravitational potential energy and binding energy<\/td>\n <td>1 question\/year<\/td>\n <td>Numerical<\/td>\n <\/tr>\n <tr>\n <td><span class=\"pyq-badge\">Low<\/span>Weightlessness and geostationary satellites<\/td>\n <td>Occasional<\/td>\n <td>Conceptual<\/td>\n <\/tr>\n <\/tbody>\n <\/table>\n <\/div>\n\n <div class=\"callout callout-tip\">\n <span class=\"callout-icon\">Tip<\/span>\n <p>NEET consistently tests the energy of orbiting satellites \u2014 specifically the relationship KE = \u2212E and PE = 2E. Master the signs and magnitudes of all three energy components (KE, PE, total) and their behaviour as orbital radius changes. This topic appears in nearly every NEET paper.<\/p>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">17<\/div>\n <h2 class=\"section-title\">Chapter <span>Summary<\/span><\/h2>\n <\/div>\n\n <p>Gravitation class 11 notes build a coherent framework from Kepler’s empirical laws through Newton’s universal law to modern satellite applications. Every major formula in the chapter \u2014 g, escape velocity, orbital velocity, satellite energy \u2014 is a direct consequence of F = GMm\/r\u00b2.<\/p>\n\n <div class=\"revision-box\">\n <h3>Quick Revision \u2014 Must-Know Points<\/h3>\n <ul>\n <li>Kepler’s third law: T\u00b2 \u221d r\u00b3; apply as (T\u2081\/T\u2082)\u00b2 = (r\u2081\/r\u2082)\u00b3 for planet comparisons.<\/li>\n <li>Newton’s law: F = Gm\u2081m\u2082\/r\u00b2. Always centre-to-centre distance. Always attractive.<\/li>\n <li>G = 6.674 \u00d7 10\u207b\u00b9\u00b9 N\u00b7m\u00b2\/kg\u00b2. Dimensions: [M\u207b\u00b9L\u00b3T\u207b\u00b2]. Universal constant.<\/li>\n <li>g = GM\/R\u00b2 at Earth’s surface \u2248 9.8 m\/s\u00b2. Independent of mass of falling body.<\/li>\n <li>g decreases with altitude: g_h \u2248 g(1 \u2212 2h\/R). Decreases with depth: g_d = g(1 \u2212 d\/R).<\/li>\n <li>g is maximum at poles and minimum at equator due to Earth’s rotation and oblate shape.<\/li>\n <li>Gravitational PE: U = \u2212GMm\/r. Always negative. Near surface: \u0394U = mgh.<\/li>\n <li>Escape velocity: v_e = \u221a(2gR) \u2248 11.2 km\/s. Independent of mass and direction.<\/li>\n <li>Orbital velocity: v_o = \u221a[GM\/(R+h)] \u2248 7.9 km\/s near surface. v_e = \u221a2 \u00d7 v_o.<\/li>\n <li>Satellite energy: KE = GMm\/2r, PE = \u2212GMm\/r, Total E = \u2212GMm\/2r. E = \u2212KE = PE\/2.<\/li>\n <li>Geostationary: T = 24 h, height \u2248 36,000 km, equatorial, west-to-east orbit.<\/li>\n <li>Weightlessness = free fall state. Gravity acts; normal force = 0.<\/li>\n <\/ul>\n <\/div>\n<\/div>\n\n\n<div class=\"section\">\n <div class=\"section-header\">\n <div class=\"badge\">18<\/div>\n <h2 class=\"section-title\">Common <span>Mistakes<\/span><\/h2>\n <\/div>\n\n <ul class=\"content-list\">\n <li><strong>Confusing G and g:<\/strong> G is the universal constant (6.674 \u00d7 10\u207b\u00b9\u00b9); g is the local acceleration (9.8 m\/s\u00b2 at surface). They are related by g = GM\/R\u00b2 but are entirely different quantities.<\/li>\n <li><strong>Using surface g formula at altitude or depth:<\/strong> Once the object is not at Earth’s surface, the formulas change. Use g_h or g_d as applicable \u2014 never plug altitude directly into g = GM\/R\u00b2.<\/li>\n <li><strong>Forgetting the negative sign in U = \u2212GMm\/r:<\/strong> The negative sign is essential. It indicates a bound system. Dropping it completely changes the physics of escape velocity and satellite energy problems.<\/li>\n <li><strong>Using wrong distance in F = Gm\u2081m\u2082\/r\u00b2:<\/strong> r is the centre-to-centre distance, not the surface-to-surface distance. For two spheres of radii R\u2081 and R\u2082 separated by gap d, use r = R\u2081 + R\u2082 + d.<\/li>\n <li><strong>Escape velocity has direction dependency:<\/strong> False. v_e is independent of the launch direction \u2014 a body launched at v_e in any direction (not just vertical) will escape, provided it doesn’t hit Earth first.<\/li>\n <li><strong>Confusing orbital velocity decrease with energy loss:<\/strong> A satellite at a higher orbit moves slower but has higher total energy (less negative). The increase in PE more than compensates for the KE decrease.<\/li>\n <li><strong>Thinking weightlessness means no gravity:<\/strong> Gravity is fully acting on an orbiting astronaut. Weightlessness is the absence of contact force (normal reaction), not absence of gravitational force.<\/li>\n <li><strong>Applying depth formula at surface:<\/strong> At the surface, d = 0, so g_d = g \u2014 this is consistent. At the centre, d = R, so g_d = 0. The formula is linear, not inverse-square inside Earth.<\/li>\n <\/ul>\n<\/div>\n\n\n<div class=\"faq-section\">\n <h2 class=\"faq-title\">Frequently Asked Questions \u2014 <span>Gravitation Class 11<\/span><\/h2>\n\n <details>\n <summary>\n What is the difference between gravitational potential and gravitational potential energy?\n <span class=\"faq-icon\">+<\/span>\n <\/summary>\n <div class=\"faq-body\">\n Gravitational potential energy (U) is the energy of a specific mass m at a point in the gravitational field: U = \u2212GMm\/r. It depends on the test mass m. Gravitational potential (V), on the other hand, is a property of the field itself at that point \u2014 it is the potential energy per unit mass: V = U\/m = \u2212GM\/r. Potential is independent of the test mass and describes the field environment. This distinction is analogous to the difference between electric potential energy and electric potential in electrostatics.\n <\/div>\n <\/details>\n\n <details>\n <summary>\n Why does g decrease both with altitude and with depth?\n <span class=\"faq-icon\">+<\/span>\n <\/summary>\n <div class=\"faq-body\">\n Above the surface, g decreases because the distance from Earth’s centre increases \u2014 the inverse-square law applies (g \u221d 1\/r\u00b2). Below the surface, only the mass enclosed within the sphere of radius (R \u2212 d) contributes to the gravitational force (shell theorem). This enclosed mass decreases as d increases, and decreases faster than the distance decreases, resulting in a net linear decrease in g. At the exact centre, all forces cancel and g = 0.\n <\/div>\n <\/details>\n\n <details>\n <summary>\n How is escape velocity derived, and why is it independent of mass?\n <span class=\"faq-icon\">+<\/span>\n <\/summary>\n <div class=\"faq-body\">\n Escape velocity is derived by setting the total mechanical energy equal to zero \u2014 the minimum condition for escape to infinity. Starting with: \u00bdmv_e\u00b2 \u2212 GMm\/R = 0, solving for v_e gives \u221a(2GM\/R). The mass m of the escaping object cancels out completely in this equation, which is why escape velocity is independent of the escaping object’s mass. It only depends on the mass M and radius R of the planet being escaped from.\n <\/div>\n <\/details>\n\n <details>\n <summary>\n What happens to the orbital speed of a satellite when it moves to a higher orbit?\n <span class=\"faq-icon\">+<\/span>\n <\/summary>\n <div class=\"faq-body\">\n Orbital speed decreases as the satellite moves to a higher orbit. From v_o = \u221a[GM\/(R+h)], as h increases, (R+h) increases, so v_o decreases. However, the time period T increases (T \u221d r^(3\/2)). This seems paradoxical because energy must be added (via rocket thrust) to move to a higher orbit, yet the satellite ends up moving slower. The explanation is that the large increase in gravitational potential energy more than accounts for the decrease in kinetic energy \u2014 total energy increases (becomes less negative).\n <\/div>\n <\/details>\n\n <details>\n <summary>\n Why do astronauts experience weightlessness in a satellite even though gravity is acting on them?\n <span class=\"faq-icon\">+<\/span>\n <\/summary>\n <div class=\"faq-body\">\n Weightlessness is the sensation caused by the absence of a contact (normal) force, not the absence of gravity. In an orbiting satellite, both the satellite and the astronaut are in the same free-fall state \u2014 they are both falling toward Earth at the same rate (the centripetal acceleration equals the local g at that altitude). Because both fall together, the satellite floor never needs to push up against the astronaut. The normal reaction is zero, creating the sensation of weightlessness. Gravity is fully present and is in fact providing the centripetal force for the orbit.\n <\/div>\n <\/details>\n\n <details>\n <summary>\n What is the significance of the negative total energy of a satellite?\n <span class=\"faq-icon\">+<\/span>\n <\/summary>\n <div class=\"faq-body\">\n The negative total energy (E = \u2212GMm\/2r) signifies that the satellite is gravitationally bound to Earth \u2014 it cannot escape without additional energy input. The magnitude of the total energy equals the binding energy: the minimum energy that must be supplied to free the satellite from its orbit and send it to infinity. If total energy were zero, the satellite would be at the escape threshold. If positive, the object would have already escaped. This sign convention is universal for all bound gravitational systems, including planetary orbits.\n <\/div>\n <\/details>\n<\/div>\n\n\n<div class=\"section\" style=\"padding-top:0; border-bottom:none;\">\n <div class=\"related-links\">\n <h4>Recommended Courses and Study Materials<\/h4>\n <ul>\n <li><a href=\"https:\/\/courses.ksquare.co.in\/new-courses\/31-umeed-neet-2026\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">Umeed NEET 2026 Study Materials<\/a><\/li>\n <li><a href=\"https:\/\/courses.ksquare.co.in\/new-courses\/29-pc4-29\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">Grip NCERT Biology<\/a><\/li>\n <li><a href=\"https:\/\/courses.ksquare.co.in\/new-courses\/28-grip-ncert-chemistry\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">Grip NCERT Chemistry<\/a><\/li>\n <\/ul>\n <\/div>\n<\/div>\n\n\n<div class=\"cta-section\">\n <h2>Ready to Score Full Marks in Gravitation?<\/h2>\n <p>Gravitation class 11 notes are complete \u2014 now it is time to practise. Use our NEET rank predictor, join the Mission 180 Physics batch, or download free study materials to push your preparation further.<\/p>\n <div class=\"cta-btns\">\n <a href=\"https:\/\/courses.ksquare.co.in\/new-courses\/3-mission-180-neet-physics-rankers-batch\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" class=\"btn-white\">Join Mission 180 Physics Batch<\/a>\n <a href=\"https:\/\/ksquareinstitute.in\/neet-2026-rank-predictor\/\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" class=\"btn-outline\">Use NEET 2026 Rank Predictor<\/a>\n <a href=\"https:\/\/ksquareinstitute.in\/free-study-material\/\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" class=\"btn-outline\">Download Free Materials<\/a>\n <\/div>\n<\/div>\n\n<\/article>\n<\/body>\n<\/html>\n\n\n\n<!DOCTYPE html>\n<html lang=\"en\">\n<head>\n <meta charset=\"UTF-8\">\n <meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\">\n <title>Table of Contents \u2014 Physics Class 11<\/title>\n \n \n <link rel=\"preconnect\" href=\"https:\/\/fonts.googleapis.com\">\n <link rel=\"preconnect\" href=\"https:\/\/fonts.gstatic.com\" crossorigin>\n <link href=\"https:\/\/fonts.googleapis.com\/css2?family=DM+Sans:ital,opsz,wght@0,9..40,100..1000;1,9..40,100..1000&family=Plus+Jakarta+Sans:ital,wght@0,200..800;1,200..800&display=swap\" rel=\"stylesheet\">\n \n <style>\n \/* Scoped wrapper using a unique ID to prevent CSS conflicts. *\/\n #physics-toc-wrapper {\n font-family: 'DM Sans', sans-serif;\n width: 100%;\n margin: 0;\n padding: 60px 0;\n color: #111;\n background: #fff;\n -webkit-font-smoothing: antialiased;\n }\n\n #physics-toc-wrapper .container-inner {\n width: 100%;\n margin: 0 auto;\n padding: 0; \/* Set left\/right padding to 0 *\/\n }\n\n #physics-toc-wrapper h1 {\n font-family: 'Plus Jakarta Sans', sans-serif;\n font-size: 0.85rem;\n font-weight: 700;\n color: #71717a;\n margin: 0 0 8px;\n letter-spacing: 0.1em;\n text-transform: uppercase;\n padding-left: 16px; \/* Keeping a small offset for headings so they aren't touching the screen edge *\/\n }\n\n #physics-toc-wrapper h2 {\n font-family: 'Plus Jakarta Sans', sans-serif;\n font-size: 2.25rem;\n font-weight: 800;\n margin: 0 0 48px;\n letter-spacing: -0.02em;\n color: #09090b;\n padding-left: 16px; \/* Keeping a small offset for headings *\/\n }\n\n #physics-toc-wrapper table {\n width: 100%;\n border-collapse: collapse;\n border-spacing: 0;\n \/* Border-left and border-right set to none or removed if you want it truly edge-to-edge with the screen *\/\n border-top: 1px solid #e4e4e7;\n border-bottom: 1px solid #e4e4e7;\n }\n\n #physics-toc-wrapper tr {\n border-bottom: 1px solid #e4e4e7;\n transition: all 0.2s ease;\n }\n\n #physics-toc-wrapper tr:hover {\n background-color: #f8fafc;\n }\n\n #physics-toc-wrapper tr:last-child {\n border-bottom: none;\n }\n\n #physics-toc-wrapper td {\n padding: 24px 16px;\n vertical-align: middle;\n font-size: 1.05rem;\n font-weight: 500;\n border-right: 1px solid #e4e4e7;\n }\n\n #physics-toc-wrapper td:last-child {\n border-right: none;\n }\n\n \/* First column (Numbers) alignment and padding *\/\n #physics-toc-wrapper td:first-child {\n color: #a1a1aa;\n font-size: 0.9rem;\n width: 70px;\n font-weight: 400;\n font-variant-numeric: tabular-nums;\n text-align: center;\n padding-left: 10px;\n }\n\n \/* Middle column (Chapter Name) alignment and padding *\/\n #physics-toc-wrapper td:nth-child(2) {\n padding-left: 24px;\n color: #18181b;\n }\n\n \/* Last column (Button) alignment and padding *\/\n #physics-toc-wrapper td:last-child {\n text-align: right;\n width: 180px;\n padding-right: 16px;\n }\n\n \/* Button Styling *\/\n #physics-toc-wrapper a.go {\n display: inline-block;\n font-family: 'Plus Jakarta Sans', sans-serif;\n font-size: 0.75rem;\n font-weight: 800;\n padding: 12px 24px;\n border: 1.5px solid #18181b;\n border-radius: 8px;\n color: #18181b;\n text-decoration: none;\n letter-spacing: 0.05em;\n text-transform: uppercase;\n transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);\n white-space: nowrap;\n }\n\n #physics-toc-wrapper a.go:hover {\n background: #18181b;\n color: #ffffff;\n transform: translateY(-2px);\n box-shadow: 0 4px 12px rgba(24, 24, 27, 0.15);\n }\n\n \/* Responsive adjustments *\/\n @media (max-width: 768px) {\n #physics-toc-wrapper h2 {\n font-size: 1.75rem;\n margin-bottom: 32px;\n }\n #physics-toc-wrapper td {\n padding: 18px 12px;\n font-size: 0.95rem;\n }\n }\n <\/style>\n<\/head>\n<body>\n\n<div id=\"physics-toc-wrapper\">\n <div class=\"container-inner\">\n <h1>Table of Contents<\/h1>\n <h2>Physics — Class 11<\/h2>\n \n <table>\n <tr><td>01<\/td><td>Units and Measurements<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/units-and-measurements-class-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>02<\/td><td>Motion in a Straight Line<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/motion-in-a-straight-line-class-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>03<\/td><td>Motion in a Plane<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/motion-in-a-plane-class-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>04<\/td><td>Laws of Motion<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/laws-of-motion-class-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>05<\/td><td>Work, Energy and Power<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/work-energy-and-power-class-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>06<\/td><td>System of Particles and Rotational Motion<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/system-of-particles-and-rotational-motion-class-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>07<\/td><td>Gravitation<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/gravitation-class-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>08<\/td><td>Mechanical Properties of Solids<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/mechanical-properties-of-solids-class-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>09<\/td><td>Mechanical Properties of Fluids<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/mechanical-properties-of-fluids-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>10<\/td><td>Thermal Properties of Matter<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/thermal-properties-of-matter-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>11<\/td><td>Thermodynamics<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/thermodynamics-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>12<\/td><td>Kinetic Theory<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/kinetic-theory-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>13<\/td><td>Oscillations<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/oscillations-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <tr><td>14<\/td><td>Waves<\/td><td><a class=\"go\" href=\"https:\/\/ksquareinstitute.in\/blog\/waves-11-notes\" target=\"_blank\">Go to page<\/a><\/td><\/tr>\n <\/table>\n <\/div>\n<\/div>\n\n<\/body>\n<\/html>\n","protected":false},"excerpt":{"rendered":"<p>Gravitation Class 11 Notes | NEET Physics Complete Guide 01 Introduction to Gravitation These Gravitation class 11 notes cover one of the most conceptually rich and NEET-relevant chapters in Class 11 Physics. Gravitation is the universal force of attraction that acts between every two objects possessing mass. It governs why an apple falls to the […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[127],"tags":[],"class_list":["post-3943","post","type-post","status-publish","format-standard","hentry","category-free-study-material"],"blocksy_meta":{"page_structure_type":"type-1","styles_descriptor":{"styles":{"desktop":"","tablet":"","mobile":""},"google_fonts":[],"version":6}},"_links":{"self":[{"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/posts\/3943","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/comments?post=3943"}],"version-history":[{"count":2,"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/posts\/3943\/revisions"}],"predecessor-version":[{"id":4210,"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/posts\/3943\/revisions\/4210"}],"wp:attachment":[{"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/media?parent=3943"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/categories?post=3943"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ksquareinstitute.in\/blog\/wp-json\/wp\/v2\/tags?post=3943"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}