Class 11 · Chapter 8

Gravitation

Overview, notes, short notes, formula sheet, daily practice problems, previous year questions, and videos for this chapter — all in one place.

Gravitation JEE Notes

3 min read

Fully worked, JEE-style problems on gravitational fields, satellite motion, and escape velocity — the multi-step derivations JEE Main and JEE Advanced build entire questions around, going a level beyond the regular DPP.

Illustration 1 — Finding a Planet's Mass from g and R

The acceleration due to gravity on a planet's surface is 4 m/s², and its radius is 3.2 × 10⁶ m. Find the mass of the planet. (G = 6.674 × 10⁻¹¹ N·m²/kg²)

Illustration 2 — Height Where g Drops to a Given Percentage

At what height above Earth's surface does the acceleration due to gravity reduce to 64% of its surface value? (Radius of Earth = 6400 km)

Illustration 3 — Orbital Speed and Period at a Given Height

Find the orbital speed and time period of a satellite orbiting at a height of 1600 km above Earth's surface. (Radius of Earth = 6400 km, g = 10 m/s²)

Illustration 4 — Escape Velocity from Earth

Find the escape velocity from Earth's surface. (R = 6400 km, g = 10 m/s²)

Illustration 5 — Energy Needed to Send a Satellite to Infinity

A 1000 kg satellite orbits Earth at a radius of 2R (twice Earth's radius). Find the minimum energy needed to send it from this orbit to infinity. (R = 6400 km, g = 10 m/s²)

Illustration 6 — Variation of g with Depth

Find the acceleration due to gravity at a depth equal to half of Earth's radius. (g at surface = 10 m/s²)

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