Physics

Gravitation and Center of Mass

368 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

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

Multiple choice

The acceleration due to gravity is zero at the

  1. poles

  2. equator

  3. centre of Earth

  4. tropics
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

At the center of the Earth, the gravitational pull from all directions cancels out, resulting in a net gravitational acceleration of zero. At the poles and equator, gravity is present, though it varies slightly due to the Earth's rotation and shape.

Multiple choice

The weight of a body at the centre of the earth is

  1. increased

  2. neutralised

  3. decreased

  4. the same
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Weight is 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 would be minimum when it is placed?

  1. At the equator

  2. At the center of the earth

  3. At the north pole

  4. None of these

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

Weight is the force exerted by 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 mass of Venus is

  1. 1/5 times that of earth

  2. 2/5 times that of earth

  3. 3/5 times that of earth

  4. 4/5 times that of earth
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The mass of venus is 4/5 times that of earth

Multiple choice

The force of gravity on the moon is

  1. the same as on the earth

  2. less than on the earth as the moon has a smaller mass

  3. there is no gravitational force at all

  4. more than the earth
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The gravitational acceleration on the surface of the Moon is 1.63 m/s2, about 16.7% that on Earth's surface. 

Multiple choice

Gravitational force is acting

  1. on other planets

  2. on all bodies

  3. only on moon

  4. only on human beings
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Gravitational force is acting on all bodies containing mass.

Multiple choice

Why a body weighs less on moon than on earth?

  1. There is less force of gravity on moon.

  2. There is no atmosphere on moon.

  3. Moon is farther away from Sun.

  4. Moon has more gravitational force.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Yes, it is correct. Moon's gravitational force is lesser than that of earth. The mass remains unchanged but the weight changes which depends on gravitational force.

Multiple choice

If the earth stops spinning about its own axis, what will be the change in acceleration due to gravity on the equator? Given the angular speed is 7.27 × 10-5 rad/sec.

  1. 3.38 cm/s2

  2. 4.45 cm/s2

  3. 3.0 cm/s2

  4. 5.55 cm/s2
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Effective acceleration due to gravity is given by, g’ = g-Rω2 cos2Ө. Hence, change in acceleration due to gravity is given as, ∆g = g’-g = - Rω2 cos2Ө At equator Ө = 0. Hence, g’-g = -R ω2 = -6.4×106× (7.27×10-5)2 = -0.0338 m/s2 Or, g’-g = -3.38 cm/s2 The (-) ve sign signifies that the decrease in gravitational acceleration is due to the rotation of earth.