physics : class11 Gravitational Force between Spherical Bodies : Gravitational Force : Gravitation MCQ Questions and Answers
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Gravitational Force between Spherical Bodies
MCQ questions and answers.
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MCQ Questions
1. Two uniform spherical bodies of masses M and m have their centres separated by distance r. What is the gravitational force between them?
A.
G(M + m)/r^2
B.
GMm/r^2
C.
GMm/r
D.
G(M - m)/r^2
Correct Answer:
GMm/r^2
Explanation:
For two spherical bodies treated as point masses at their centres, Newton's law of gravitation gives F = GMm/r^2.
2. For two spherical bodies, the distance used in Newton's law of gravitation is measured between their:
A.
Surfaces
B.
Edges
C.
Centres
D.
Diameters
Correct Answer:
Centres
Explanation:
The gravitational force between spherical bodies is calculated using the distance between their centres.
3. If the distance between the centres of two spherical bodies is doubled, their gravitational force becomes:
A.
Four times
B.
Two times
C.
One-half
D.
One-fourth
Correct Answer:
One-fourth
Explanation:
Since gravitational force varies inversely as the square of the centre-to-centre distance, doubling the distance makes the force one-fourth.
4. If the mass of one spherical body is doubled while the other mass and centre-to-centre distance remain unchanged, the gravitational force becomes:
A.
Half
B.
Double
C.
Four times
D.
Unchanged
Correct Answer:
Double
Explanation:
The gravitational force is directly proportional to each mass, so doubling one mass doubles the force.
5. Two spherical bodies have masses 2 kg and 3 kg, and their centres are 1 m apart. Their gravitational force is:
A.
6G N
B.
5G N
C.
G/6 N
D.
G/5 N
Correct Answer:
6G N
Explanation:
Using F = GMm/r^2, F = G(2)(3)/(1)^2 = 6G N.
6. A uniform spherical shell attracts an external object as if the entire mass of the shell were concentrated at its:
A.
Surface
B.
Centre
C.
Uppermost point
D.
Nearest point on the shell
Correct Answer:
Centre
Explanation:
By the shell theorem, the gravitational effect of a uniform spherical shell on an external object is the same as if its mass were concentrated at the centre.
7. Two spherical bodies exert gravitational forces on each other that are:
A.
Equal in magnitude and opposite in direction
B.
Equal in magnitude and in the same direction
C.
Unequal in magnitude and opposite in direction
D.
Zero in magnitude and opposite in direction
Correct Answer:
Equal in magnitude and opposite in direction
Explanation:
The gravitational interaction between two spherical bodies follows Newton's third law: the forces are equal in magnitude and opposite in direction.
8. If the masses of both spherical bodies are doubled while their centre-to-centre distance remains unchanged, the gravitational force becomes:
A.
Two times
B.
Four times
C.
Half
D.
Unchanged
Correct Answer:
Four times
Explanation:
Since F is proportional to the product of the two masses, doubling both masses multiplies the force by 2 × 2 = 4.
9. The gravitational force between two spherical bodies acts along the line joining their:
A.
Surfaces
B.
Radii
C.
Centres
D.
Diameters only
Correct Answer:
Centres
Explanation:
For spherical bodies, the gravitational force acts along the line joining their centres.
10. A spherical body of mass M and radius R attracts a small object outside it at a distance r from its centre. The gravitational force is:
A.
GMr^2
B.
GMR^2
C.
GM/r^2
D.
GM/R^2
Correct Answer:
GM/r^2
Explanation:
Outside a spherical body, its gravitational effect is the same as that of a point mass M at its centre, so F = GM/r^2.
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