Gravitation

Move from Newton's law to field, potential, escape speed, and satellite motion with a JEE-centered understanding of gravitational systems.

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JEE Intro

How to Think About Gravitation

Move from Newton's law to field, potential, escape speed, and satellite motion with a JEE-centered understanding of gravitational systems.

This chapter is written as original Learn at My Place teaching copy. The aim is to give you the JEE decision-making layer: what equation to trust, what approximation is valid, and where exam traps usually appear.

Read the full note once, then revisit the quick revision block before solving your own practice questions.

Problem Method

How to Solve Gravitation Questions

1. Model the Situation

Draw the body, path, field, graph, or interaction first. Label known quantities and choose sign convention before writing equations.

2. Pick the Governing Law

Decide whether the problem is about conservation, force balance, energy, momentum, fields, or graph interpretation.

3. Check the Edge Case

Verify units, limiting values, direction, and whether approximation assumptions are valid for JEE Main and Advanced options.

Section A

Notes: Gravitation

Original teaching copy for Learn at My Place

1. Universal Gravitation, Field, and Potential 2. Variation of g, Satellite Motion, and Escape Speed

1. Universal Gravitation, Field, and Potential

The force between two masses is:

F = G\frac{m_1m_2}{r^2}

It is always attractive and acts along the line joining the masses.

Gravitational field and potential due to a point mass $M$ are:

g = \frac{GM}{r^2}, \qquad V = -\frac{GM}{r}

The negative sign in potential matters because zero is taken at infinity.

2. Variation of g, Satellite Motion, and Escape Speed

For small height $h$ above Earth, $g$ decreases approximately as $g_h \approx g(1-2h/R)$ . For depth $d$ inside a uniform Earth model, $g_d = g(1-d/R)$ .

For a circular orbit of radius $r$ :

v_o = \sqrt{\frac{GM}{r}}, \qquad T = 2\pi\sqrt{\frac{r^3}{GM}}

Escape velocity from the surface is:

v_e = \sqrt{2gR}

Quick Revision

Last 5-Minute Recall

JEE exam rule: First identify the governing principle. Most errors happen because students choose the wrong framework before they start the algebra.

Newton's inverse-square law

Field and potential as two complementary viewpoints

Variation of g with height and depth

Orbital speed, time period, and escape velocity

Verified question bank

Gravitation questions with answers

Open any of these 81 quality-checked JEE questions to review all four options, the correct answer, and the worked explanation.

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