Physics

Gravitation and Center of Mass

369 Questions

Gravitation and center of mass questions explore gravitational fields, planetary density, and the mechanics of celestial bodies. Test items include calculating gravitational strength on different planets and understanding the Roche Limit. This topic is essential for the physics syllabus of major competitive exams.

Gravitational fieldCenter of massPlanetary densityHill SphereSpace-time curvature

Gravitation and Center of Mass Questions

Multiple choice

When an object is transferred from the earth to the moon?

  1. Its weight increases

  2. Its mass increases

  3. Its mass decreases

  4. Its weight decreases & its mass remains constant

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mass is an intrinsic property that doesn't change with location. Weight depends on gravitational force, which is much weaker on the Moon (about 1/6th of Earth's gravity). So weight decreases significantly while mass remains constant.

Multiple choice

Which of the following statements is false regarding the gravitational force?

  1. The planets revolve around the Sun in uniform motion due to presence of gravitational force.

  2. There is presence of atmosphere on the earth due to gravitational force.

  3. Tides in seas and oceans are due to gravitational force.

  4. It keeps the moon in orbit around the earth.

  5. None of these
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Yes, this is the correct answer as all the above statements are true. None of them is false regarding the gravitational force.

Multiple choice

How does the gravitational force vary with the nature or properties of the medium in which the masses are placed?

  1. It remains constant

  2. It increases in a denser medium

  3. It decreases in a denser medium

  4. It becomes zero in rarer medium

  5. It becomes zero in denser medium
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Yes, it is the correct answer. The value of gravitational constant is same for any pair of masses in the universe but the value of G does not depend on the nature or properties of the medium in which the masses are placed. So, that is why the value of G is constant everywhere in universe.

Multiple choice

The gravitational force between two objects is directly proportional to the masses of the objects and inversely proportional to the square of the distance between them. This law is called as_______.

  1. Snell's law

  2. Lenz's law

  3. Universal law of gravitation

  4. Faraday's law
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Newton's Universal Law of Gravitation states that every particle attracts every other particle with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. This is a fundamental law of physics.

Multiple choice

If a person jumps on earth, he jumps little but when a person jumps on moon he can jump higher. Why?

  1. Gravitation pull on the moon's surface is lower than that of the earth

  2. Moon has no atmosphere

  3. Moon has no medium

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The gravitational pull on the Moon is about 1/6th of Earth's gravity. With weaker gravitational force, a person can jump much higher and further on the lunar surface. This is why astronauts appeared to bounce on the Moon.

Multiple choice

What is the weight of the moon?

  1. 1/4 of the earth

  2. 1/5 of the earth

  3. 1/6 of the earth

  4. 1/8 of the earth

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The Moon's mass is approximately 1/6th that of Earth, which is why astronauts weigh much less on the lunar surface. This ratio also explains why the Moon's gravity is about 16.6% of Earth's. The other fractions (1/4, 1/5, 1/8) are incorrect.

Multiple choice

Mass of Earth is ________ times that of moon.

  1. 51

  2. 61

  3. 71

  4. 81
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Earth's mass is approximately 81 times that of the Moon. This mass ratio is responsible for the Moon orbiting Earth rather than the other way around, as the more massive object exerts the stronger gravitational pull.

Multiple choice

The weight of a substance on the moon is

  1. 1/8th of its weight on the earth

  2. 1/7th of its weight on the earth

  3. 1/6th of its weight on the earth

  4. <font face="Arial" size="2">1/5th of its weight on the earth</font>
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice

Which of the following statements is/are correct?

a. The ‘tide-generating’ force is the difference between the gravitational attraction of the moon and the centrifugal force. b. On the surface of Earth, the horizontal tide generating forces are less dominant than the vertical forces in generating the tidal bulges. c. The gravitational pull of Earth creates the second bulge away from the moon.

  1. a only

  2. b only

  3. c only

  4. a and b

  5. b and c
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is the correct answer.

Multiple choice

On earth, the weight of an object is

  1. minimum at the poles

  2. constant in every place

  3. maximum at the equator

  4. maximum at the poles
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Earth is not a perfect sphere but an oblate spheroid, bulging at the equator. The gravitational force (which determines weight) is inversely proportional to the square of the distance from Earth's center. Since the poles are closer to the center than the equator, weight is maximum at the poles and minimum at the equator for the same mass.

Multiple choice

The weight of an object would be minimum when it is placed

  1. at the equator

  2. at the North Pole

  3. at the South Pole

  4. at the centre of the earth
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Weight is defined as the force of gravity on an object. At the center of the Earth, the gravitational pull from all directions cancels out, resulting in zero weight.

Multiple choice

The weight of an object will be minimum when it is placed at

  1. The North Pole

  2. The South Pole

  3. The Equator

  4. The center of the Earth
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Weight is the force of gravity acting on an object. At the center of the Earth, the gravitational pull from all directions cancels out, making the effective weight of an object zero (the minimum possible).

Multiple choice

Centre of mass is

  1. a point

  2. both scaler and vector

  3. scalar

  4. vector
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Centre of mass of a body is the point at which whole mass of the body is concentrated