NCERT  ·  Physics  ·  Ch.9

Gravitation

Universal Gravitation · g on Earth & Moon · Mass & Weight · Pressure · Buoyancy · Archimedes & Density

50
Questions
45 min
Duration
3
Tiers
5
Topics
⚡ Begin Analytics
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Question Intelligence

Quiz Analytics

A data-driven breakdown of all 50 questions by difficulty, exam origin and topic distribution.

📈 Distribution Overview

50
Total Questions
Concept Check (NCERT)
34
Law & Relation Reasoning
12
Straightforward Numericals
4

🗂 Topic Coverage

Universal Law & Gravity Basics
20%
g, Mass, Weight & Free Fall
24%
Thrust, Pressure & Fluids
16%
Buoyancy & Archimedes Principle
24%
Density & Relative Density
16%
34
Concept Check (NCERT)
12
Law & Relation Reasoning
4
Straightforward Numericals
Conceptual Framework

Key Concept Highlights

6 foundational pillars that power every question in this quiz. Understand these, and the answers follow naturally.

🌍
Universal Law of Gravitation
Any two objects in the universe attract each other with a gravitational force directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres.
⬇️
Acceleration due to Gravity, Mass & Weight
Acceleration due to gravity g on Earth is about 9.8 m/s², depends on planet (mass and radius) but not on the falling body’s mass, while weight is the gravitational force mg and mass is the amount of matter.
📏
Thrust & Pressure in Fluids
Thrust is the normal force acting on a surface and pressure is thrust per unit area, with fluid pressure at rest increasing with depth and being measured in pascal (Pa) in SI units.
💧
Buoyancy & Archimedes’ Principle
A body immersed in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced, explaining why some objects float while others sink and forming the basis of Archimedes’ principle.
⚖️
Density & Relative Density
Density is mass per unit volume, while relative density is a ratio of the density of a substance to the density of water and therefore has no unit, helping predict floating and sinking behaviour.
🌙
g on Moon & Weightlessness
Acceleration due to gravity on the Moon is about one-sixth that on Earth, making weights smaller there, and weightlessness occurs when a body is in free fall with no normal reaction from a support.
Pedagogical Value

Why MCQs Matter

Multiple-choice questions are not mere guessing games — they are the sharpest diagnostic tool available to a competitive exam aspirant.

  • Force precise recall — vague conceptual understanding gets exposed immediately
  • Train elimination logic, a critical skill in JEE where partial knowledge suffices
  • Mirror CBSE Board objective and JEE Main Paper 1 formats exactly
  • Build decisive exam temperament — no room for hesitation
  • Reveal misconceptions that long-answer formats often mask
  • Provide instant feedback loops for targeted revision
~8–10%

of Class 9 Science Physics weightage under “Gravitation” including thrust, pressure, buoyancy and relative density.

Quick Reference

Important Formula Capsules

6 must-memorise equations that surface repeatedly across CBSE and JEE papers.

Universal Law of Gravitation
\[ F = G \dfrac{m_{1} m_{2}}{r^{2}} \]
g near Earth’s Surface
\[ g = G \dfrac{M}{R^{2}} \]
Weight of a Body
\[ W = m g \]
Pressure Definition
\[ P = \dfrac{F}{A} \]
Buoyant Force (Archimedes)
\[ F_{\text{b}} = \text{weight of displaced fluid} \]
Relative Density
\[ \text{Relative density} = \dfrac{\text{density of substance}}{\text{density of water}} \]
Learning Outcomes

What You Will Learn

By completing this quiz set you will have exercised all the following competencies.

01 State the universal law of gravitation and identify how gravitational force changes when masses or distance between bodies change.
02 Distinguish between gravitational constant G and acceleration due to gravity g, and recall standard values and units used in Class 9 questions.
03 Explain the difference between mass and weight, describe how weight varies from Earth to Moon, and relate free fall to the concept of weightlessness.
04 Define thrust and pressure, write P = F/A, and describe how fluid pressure depends on depth, density and gravitational acceleration.
05 State and apply Archimedes’ principle to decide whether a body will float or sink and to compute buoyant force and apparent weight.
06 Use density and relative density to compare substances and link these ideas to floating or sinking in water and other liquids.
07 Relate gravitational force to planetary motion, explaining qualitatively how gravity provides the centripetal force that keeps planets and satellites in their orbits.
Exam Preparation

Strategy & Preparation Tips

5 evidence-based strategies to maximise your score in CBSE Boards and JEE.

01
Step 01
Separate G, g, Mass & Weight
Make a small table clearly distinguishing G, g, mass and weight—definitions, units and typical values—to avoid mixing them up in MCQs.
02
Step 02
Think Proportionality First
For questions on how gravitational force changes, focus on the proportionalities F ∝ m₁m₂ and F ∝ 1/r² before worrying about exact numbers.
03
Step 03
Use Simple Float–Sink Rules
Remember: density object < density fluid ⇒ float; density object > density fluid ⇒ sink; connect this with relative density greater or less than 1.
04
Step 04
Visualise Forces in Fluids
Whenever you see buoyant force or apparent weight, draw arrows for weight downward and upthrust upward to reason whether the body rises, sinks or stays in equilibrium.
05
Step 05
Link Gravity to Orbits
For questions about Earth–Moon or Sun–planet motion, recall that gravitational force provides the necessary centripetal pull and that in an isolated system total momentum remains conserved.

Ready to Test Your Mastery?

50 questions  ·  Elapsed timer  ·  Instant scored results

⚡ Begin Gravitation Quiz
🎯 Knowledge Check

Physics — GRAVITATION

50 Questions Class 9 MCQs
1
The force of attraction between any two objects in the universe is called:
2
Who gave the Universal Law of Gravitation?
3
The Universal Law of Gravitation states that every object attracts every other object with a force which is:
4
What does ‘G’ represent in the Universal Law of Gravitation?
5
The value of gravitational constant (G) is:
6
The force of gravitation between two objects depends on:
7
The acceleration due to gravity on Earth is approximately:
8
The acceleration due to gravity does not depend on:
9
The value of ‘g’ is maximum at:
10
The value of ‘g’ decreases as we:
11
Weight of an object is:
12
Mass of an object is measured in:
13
Weight is measured in:
14
Which of the following quantities remains constant everywhere?
15
On the Moon, a body will weigh:
16
The Earth attracts the Moon because of:
17
The motion of the Moon around Earth is due to:
18
The universal law of gravitation helps in calculating:
19
The mass of Earth is approximately:
20
The radius of Earth is approximately:
21
The formula for gravitational force is:
22
The value of ‘g’ on the surface of Earth is obtained using formula:
23
Weightlessness occurs when:
24
The density of Earth is about:
25
Which of these has the least gravitational force?
26
The pressure exerted by a liquid column depends on:
27
The unit of pressure is:
28
Pressure in a fluid at rest increases with:
29
Buoyant force acts:
30
The upward force exerted by a liquid on a body immersed in it is called:
31
When a body is fully or partially immersed in a fluid, it experiences an upward force equal to:
32
Archimedes’ principle helps to determine:
33
Thrust is defined as:
34
SI unit of thrust is:
35
The SI unit of density is:
36
Relative density has:
37
The relative density of water is:
38
If a body floats on water, its weight is:
39
A body sinks in water when:
40
A body will float in a liquid if:
41
The loss of weight of a body immersed in a liquid is equal to:
42
An object weighs 10 N in air and 6 N in water. The buoyant force on it is:
43
The acceleration due to gravity on the Moon is approximately:
44
A freely falling body on Earth experiences:
45
The gravitational force between two bodies decreases if:
46
The path of planets around the Sun is:
47
The force which acts on the Earth and keeps it moving around the Sun is:
48
The gravitational force between two objects will become four times if:
49
If the mass of one body is doubled, the gravitational force between two bodies:
50
The gravitational force between two objects is zero when:
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Frequently Asked Questions

Gravitation is the force of attraction between any two objects in the universe.

Sir Isaac Newton formulated the Universal Law of Gravitation.

Every object attracts every other object with a force proportional to the product of their masses and inversely proportional to the square of the distance between them.

\(F=G \frac{Mm}{d^2}\), where \(G\) is gravitational constant, \(M\) and \(m\) are masses, and \(d\) is distance.

Free fall is the motion of an object under gravity only, without air resistance.

It is the acceleration produced in a body due to gravitational force, denoted by \(g\), approximately \(9.8\, m/s^2\) on Earth.

Because acceleration due to gravity is constant and does not depend on mass when air resistance is negligible.

Mass is the amount of matter; weight is the force of gravity on the mass and can vary by location.

Moon’s gravity is about 1/6th Earth's, so weight decreases but mass remains the same.

Buoyancy is the upward force exerted by a fluid that opposes the weight of an object immersed in it.

Buoyant force on an object equals the weight of the fluid displaced by it.

The Moon and Sun’s gravity pull ocean water, causing tides.

‘g’ is acceleration due to gravity, varying slightly with location on Earth.

It keeps planets, moons, and satellites in orbit, shapes galaxies, and causes tides.

Earth’s gravity pulls all objects towards its center.

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