Gravitation for NEET 2025: Most Expected Questions, Formulas & Concepts

Gravitation is one of the most fundamental and high-impact chapters in NEET Physics. As part of the Mechanics unit, it not only appears directly in the exam but also forms the base for understanding other topics like circular motion, work-energy, and even planetary motion.

Why it matters in NEET:

1–2 questions appear from this chapter in every NEET paper
Often involves direct formula-based numericals or conceptual MCQs
Mastery over Gravitation improves performance in other Mechanics topics

This blog covers:

Key formulas and concepts from Gravitation
Kepler’s Laws, orbital motion, and escape velocity
Solved NEET-style examples
High-yield tips to tackle expected question types

NEET Gravitation Chapter Weightage & Question Pattern

From NEET 2020 to 2024, Gravitation has maintained a consistent presence with 1–2 questions every year, contributing 4–8 marks.

What kind of questions appear?

Numericals on escape velocity, orbital speed, or energy
Conceptual questions on Kepler’s laws, gravitational field, or potential

Common overlaps:

Work-Energy: Energy in satellite motion
Circular Motion: Centripetal force and orbital path
Laws of Motion: Force equations involving gravitational pull

Why it’s high scoring:

Most formulas are straightforward and easy to apply
Diagrams help visualize orbital paths, field lines, and satellite mechanics
With formula memory + conceptual clarity, full marks are achievable in this unit

Universal Law of Gravitation & Basics

Newton’s Law of Universal Gravitation

This fundamental law describes the gravitational force between any two point masses.

$\boldsymbol{F = G \frac{m_1 m_2}{r^2}}$

Where:

$\boldsymbol{F}$ = gravitational force between two masses
$\boldsymbol{G = 6.67 \times 10^{-11} , \text{Nm}^2/\text{kg}^2}$ = universal gravitational constant
$\boldsymbol{m_1, m_2}$ = masses
$\boldsymbol{r}$ = distance between centers of masses

Key Points:

Inverse square law: As rrr increases, $\boldsymbol{F \propto \frac{1}{r^2}}$
Force is always attractive
Acts along the line joining the centers of the two masses
Applies to both point masses and spherically symmetric objects

Gravitational Field & Potential

These describe how a mass influences space around it.

Gravitational Field (g):

$\boldsymbol{g = \frac{GM}{r^2}}$

Where:

$\boldsymbol{g}$ = gravitational field intensity
$\boldsymbol{M}$ = mass producing the field
$\boldsymbol{r}$ = distance from the mass center

Gravitational Potential (V):

$\boldsymbol{V = -\frac{GM}{r}}$

Negative sign shows work is required to bring mass from infinity to r.

Relation between g and V:

$\boldsymbol{g = -\frac{dV}{dr}}$

This relation helps in solving conceptual NEET questions involving potential gradients.

Satellite Motion & Kepler’s Laws

Satellite in Circular Orbit

A satellite remains in orbit due to a balance between the gravitational pull of the planet and the centripetal force required for circular motion.

Step 1: Equating forces

$\boldsymbol{\frac{mv^2}{r} = \frac{GMm}{r^2} \Rightarrow v = \sqrt{\frac{GM}{r}}}$

Where:

$\boldsymbol{v}$ = orbital speed of satellite
$\boldsymbol{G, M}$ = gravitational constant and mass of the planet
$\boldsymbol{r}$ = radius of orbit (from planet’s center)

Time Period of Satellite (T):

$\boldsymbol{T = 2\pi \sqrt{\frac{r^3}{GM}}}$

This is useful in geostationary satellite problems and to verify Kepler’s 3rd law.

Kepler’s Laws Overview

Formulated by Johannes Kepler, these empirical laws describe the motion of planets and satellites.

1. Law of Orbits:

Planets move in elliptical orbits, with the Sun at one focus.

2. Law of Areas:

A planet sweeps equal areas in equal intervals of time.
→ Areal velocity is constant

3. Law of Periods:

$\boldsymbol{T^2 \propto r^3}$

The square of the time period is directly proportional to the cube of the orbit’s radius.
→ Frequently used in NEET to relate orbits of satellites

Escape Velocity, Energy, and Communication Satellites

Escape Velocity

Escape velocity is the minimum speed required for an object to escape the gravitational pull of a planet without further propulsion.

$\boldsymbol{v_e = \sqrt{\frac{2GM}{R}}}$

Where:

$\boldsymbol{G = 6.67 \times 10^{-11} , \text{Nm}^2/\text{kg}^2}$
$\boldsymbol{v_e \approx 11.2 , \text{km/s}}$
M = mass of the planet
R = radius of the planet

For Earth:

$\boldsymbol{v_e \approx 11.2 , \text{km/s}}$

This formula is frequently used in NEET for direct numerical problems.

Energy in Orbits

When a satellite is in a circular orbit, it has:

Total Mechanical Energy:

$\boldsymbol{E = -\frac{GMm}{2r}}$

A negative sign indicates bound energy (the satellite is gravitationally bound to the planet).

Kinetic Energy (K.E.):

$\boldsymbol{\text{K.E.} = \frac{GMm}{2r}}$

Potential Energy (P.E.):

$\boldsymbol{\text{P.E.} = -\frac{GMm}{r}}$

So,

$\boldsymbol{E = \text{K.E.} + \text{P.E.} = -\frac{GMm}{2r}}$

This breakdown often appears in theoretical NEET questions and matching-type MCQs.

Geostationary Satellites

A geostationary satellite is a satellite that appears stationary relative to Earth. Important points:

Time period = 24 hours
Orbit height ≈ 36,000 km above Earth’s surface
Orbits in the equatorial plane in the same direction as Earth’s rotation

Applications:

Satellite TV
Communication systems
GPS relay systems

Appears in NEET as conceptual, assertion-reason, or matching-type questions.

Must-Know Gravitation Formulas for NEET

Concept	Formula
Newton’s Law	$\boldsymbol{F = G \frac{m_1 m_2}{r^2}}$
Gravitational Field	$\boldsymbol{g = \frac{GM}{r^2}}$
Gravitational Potential	$\boldsymbol{V = -\frac{GM}{r}}$
Orbital Velocity	$\boldsymbol{v = \sqrt{\frac{GM}{r}}}$
Escape Velocity	$\boldsymbol{v_e = \sqrt{\frac{2GM}{R}}}$
Time Period of Satellite	$\boldsymbol{T = 2\pi \sqrt{\frac{r^3}{GM}}}$
Total Energy in Orbit	$\boldsymbol{E = -\frac{GMm}{2r}}$

Tip: Write these on flashcards or sticky notes for quick revision before mock tests.

NEET-Style Solved Questions with Explanation

Q1.

What is the escape velocity from the surface of a planet of mass $\boldsymbol{6 \times 10^{24} , \text{kg}}$ and radius $\boldsymbol{6.4 \times 10^6 , \text{m}}$ ?

Solution:

$\boldsymbol{v_e = \sqrt{\frac{2GM}{R}} = \sqrt{\frac{2 \times 6.67 \times 10^{-11} \times 6 \times 10^{24}}{6.4 \times 10^6}} \approx 11.2 , \text{km/s}}$

Answer: 11.2 km/s

Q2.

A satellite orbits Earth at a height where gravitational acceleration is one-fourth that on the surface. What is its orbital radius?

Solution:

We use:

$\boldsymbol{g = \frac{GM}{r^2}, \quad \frac{g'}{g} = \left( \frac{R}{r} \right)^2}$

Given $\boldsymbol{\frac{g'}{g} = \frac{1}{4}}$

So,

$\boldsymbol{\left( \frac{R}{r} \right)^2 = \frac{1}{4} \Rightarrow \frac{R}{r} = \frac{1}{2} \Rightarrow r = 2R}$

Answer: $\boldsymbol{r = 2R}$

Preparation Tips to Master Gravitation

✔️ Memorize formulas: Most questions in NEET are formula-application based.
Create a one-pager with all formulas for regular revision.

✔️ Practice escape velocity and satellite numericals: These are the most commonly tested in NEET.

✔️ Understand concepts before solving: Don’t just mug up derivations—understand the why behind them to apply better.

✔️ Use diagrams frequently: Especially for satellite motion, gravitational field direction, and orbital energy systems.

✔️ Solve NEET PYQs: Patterns often repeat. Identify how questions are framed around gravitation laws and energy.

Use mock tests and timed problem sets to build speed and accuracy in this chapter.

FAQs on Gravitation for NEET

Q: How many questions come from Gravitation in NEET?

A: Usually 1–2 questions are asked from this chapter in every NEET paper. These questions are often numerical, focusing on formula application (like escape velocity, orbital energy, or gravitational potential).

Q: Are the derivations important?

A: Not for NEET. You should understand the logic behind derivations once during your preparation, but NEET questions will only test your conceptual understanding and ability to apply formulas, not the steps of derivation.

Q: What should I focus on most in Gravitation?

A: Prioritize the following:

Gravitational field and potential: Direct formula-based questions are common
Escape velocity: Frequently asked numerically with changing planetary values
Satellite motion: Orbital velocity, total energy, and Kepler’s laws appear regularly

Mastering these ensures you’re ready for nearly every question NEET might ask from this chapter.

Conclusion

Gravitation is a concept-rich yet straightforward chapter in NEET Physics. With just a few powerful formulas and clear understanding, it becomes one of the easiest scoring topics in Mechanics.