🔬
CBSE Pattern
Gravitation carries 5-7 marks in CBSE. Expect: 1 long-answer derivation (3-5M), 1-2 short answer (2M each), 1 MCQ (1M). Derivations are predictable — they've repeated for years.
Most Repeated Derivations (Last 10 Years)
Kepler's 3rd Law derivation
9/10
g from Newton's law (g=GM/R²)
8/10
Escape velocity derivation
8/10
Variation of g at height
7/10
Orbital velocity derivation
6/10
Weightlessness definition
5/10
Satellite total energy
4/10
Repeated PYQ Examples
📅 CBSE 2023
Derive an expression for the escape velocity of an object from the surface of the Earth. How is it related to orbital velocity near Earth's surface?
3 MarksDerivation
📅 CBSE 2022
Show that for a planet in elliptical orbit, the areal velocity is constant. What physical quantity is conserved?
2 MarksConceptual
📅 CBSE 2021
Using Newton's law of gravitation, obtain an expression for g. Calculate the gravitational force on the Moon due to Earth. (Given data)
5 MarksDerivation + Numerical
📅 CBSE 2020
The time period of a satellite of Earth is 5 hours. If the separation between Earth and satellite is increased to 4 times the original value, find the new time period.
2 MarksKepler's 3rd Law
🎯
CBSE Strategy
Prepare these 5 derivations word-for-word: (1) g=GM/R², (2) Kepler's 3rd law, (3) Escape velocity, (4) Orbital velocity, (5) Satellite total energy. These 5 derivations cover 70% of CBSE Gravitation marks over 10 years.
🔬
NEET Pattern
NEET asks 2-3 MCQs from Gravitation per year. Mostly conceptual + direct formula. Speed matters — solve in under 90 seconds. Topics rotate between g-variation, satellites, escape velocity, and Kepler's laws.
NEET Topic Frequency (2015-2024)
Variation of g (height/depth)
17
Orbital velocity/period
15
Hot Patterns in NEET
🔥 g at height vs depth comparison 🔥 Kepler's T₁/T₂ ratio 🔥 Satellite energy relations ⚡ Escape velocity on different planets ⚡ Geostationary satellite properties ⚡ g at Earth's center Angular momentum in orbit Shell theorem application
❌
NEET Trap Questions
"g decreases more with altitude than depth" (TRUE for same distance). "Escape velocity depends on angle of projection" (FALSE — independent). "g=0 means no gravity" (FALSE — apparent weight=0).
NEET PYQ Examples (Solved)
📅 NEET 2023
If the radius of Earth is reduced to half, keeping mass constant, the escape velocity would become:
(A) 2Vₑ (B) √2 Vₑ (C) 4Vₑ (D) Vₑ/2
Answer: (B) √2 Vₑ
Vₑ = √(2GM/R). If R → R/2 (M constant): Vₑ' = √(2GM/(R/2)) = √(4GM/R) = √2 × √(2GM/R) = √2 Vₑ
NEET 2023Direct Formula
📅 NEET 2022
Two satellites of Earth, S₁ and S₂ are moving in the same orbit. The mass of S₁ is four times the mass of S₂. The orbital velocity of S₁ is:
(A) 4v₂ (B) v₂/4 (C) v₂ (D) 2v₂
Answer: (C) v₂
Orbital velocity v₀ = √(GM/r) — INDEPENDENT of satellite's mass. Both satellites at same orbital radius → same v₀.
NEET 2022Conceptual Trap
📅 NEET 2020
A body weighs 200N on the surface of Earth. How much it will weigh halfway down to the centre of Earth?
Answer: 100 N
g_d = g(1−d/R). At d=R/2: g_d = g/2. Weight = mg_d = 200/2 = 100 N
NEET 2020Direct Formula
🔬
JEE Main Pattern
JEE Main asks 1-2 questions per paper from Gravitation. Mix of formula application and conceptual. Since 2019 (NTA era), numerical answer type (NAT) questions increased. Satellite energy, escape velocity density form, and Kepler's law ratio problems are frequent.
JEE Main High-Frequency Topics
Satellite energy (KE, PE, Total)
HIGH
Kepler's 3rd law numericals
HIGH
g variation (altitude/depth)
MED
Gravitational potential/field
MED
Escape velocity density form
MED
Question Type Distribution (JEE Main)
JEE Main PYQ Examples
📅 JEE Main 2023 (Jan)
The ratio of escape velocity of Earth to that of a planet whose radius is double and mean density is same as Earth is:
Answer: 1:2
Vₑ = R√(8πGρ/3). Same ρ → Vₑ ∝ R. If R_planet = 2R_earth → Vₑ_planet = 2Vₑ_earth. Ratio = 1:2
JEE Main 2023Density Form
📅 JEE Main 2022 (June)
A satellite is in circular orbit of radius r. The energy required to transfer it to another circular orbit of radius 4r is E₀. The energy required to transfer it from radius r to radius 2r would be:
Answer: 2E₀/3
E from r to 4r: ΔE = GMm(1/r−1/4r)/2 = 3GMm/8r = E₀. E from r to 2r: GMm(1/r−1/2r)/2 = GMm/4r = 2E₀/3 (as E₀ = 3GMm/8r)
JEE Main 2022Multi-step
🔬
JEE Advanced Pattern
JEE Advanced uses Gravitation to test multi-concept thinking. Binary star systems, tunnel SHM, elliptical orbits, paragraph-based problems with 3-4 sub-questions. Multiple-correct MCQs are common. Expect combined Gravitation + Circular Motion + Angular Momentum problems.
JEE Advanced Patterns (2015–2024)
🔥 Binary Star System (2015, 2017, 2019) 🔥 Elliptical Orbit + Energy (2016, 2020, 2022) 🔥 Tunnel SHM (2014, 2018) ⚡ Gravitational potential (solid sphere) (2021) ⚡ Kepler's 2nd law + angular momentum (2023) Orbital transfer energy (2013, 2024) Variable g problems
📅 JEE Advanced 2020
A planet P moves in an elliptical orbit around a fixed star S. The planet is at distances r₁ and r₂ from the star at perihelion and aphelion respectively. If v₁ and v₂ are the velocities of the planet at perihelion and aphelion respectively, then (multiple correct):
(A) v₁r₁ = v₂r₂ (B) v₁ > v₂ (C) v₁r₁² = v₂r₂² (D) E_total = constant
Answers: (A), (B), (D)
(A) Angular momentum conservation: L = mvr → v₁r₁ = v₂r₂ ✓. (B) At perihelion (closest) → maximum speed ✓. (C) Wrong — conservation of L, not L². (D) Energy is conserved in orbit ✓.
JEE Advanced 2020Multi-correct
📅 JEE Advanced 2017
A binary star consists of two stars A (mass 2M) and B (mass M). They revolve in circular orbits about their common centre of mass in free space. If the time period is T, find the orbital speed of star A.
v_A = (2πd/3T) where d = separation
COM: r_A = d/3, r_B = 2d/3. ω = 2π/T. v_A = ω·r_A = (2π/T)(d/3) = 2πd/3T
JEE Advanced 2017Binary Star
🧠
JEE Advanced Thinking
In JEE Advanced, Gravitation is rarely tested in isolation. Binary stars = Gravitation + Circular Motion + Angular Momentum. Elliptical orbit = Gravitation + Energy Conservation + Kepler's Laws. Always ask: "Which other concepts apply here?"