Gravitation · Question 55

The density of a newly discovered planet is twice that of earth. The acceleration due to gravity at the surface of the planet is equal to that at the surface of the earth. If the radius of the earth is R, the radius of the planet would be

1. 2R
2. 4R
3. 14R
4. 12R

Two spheres of masses m and M are situated in air and the gravitational force between them is F. The space around the masses is now filled with a liquid of specific gravity 3. The gravitational force will now be

1. 3F
2. F
3. F/3
4. F/9

The acceleration due to gravity on the planet A is 9 times the acceleration due to gravity on planet B. A man jumps to a height of 2 m on the surface of A. What is the height of jump by the same person on the planet B?

1. (2/9) m
2. 18 m
3. 6 m
4. (2/3) m

A body of mass m is placed on earth's surface which is taken from earth surface to a height of h = 3R, then change in gravitational potential energy is

1. mgR4
2. 23mgR
3. 34mgR
4. mgR2

With what velocity should a particle be projected so that its height becomes equal to radius of earth?

1. ( GMR )1/2
2. ( 8GMR )1/2
3. ( 2GMR )1/2
4. ( 4GMR )1/2

For a planet having mass equal to mass of the earth but radius is one fourth of radius of the earth. Then escape velocity for this planet will be

1. 11.2 km/s
2. 22.4 km/s
3. 5.6 km/s
4. 44.8 km/s

A body of weight 72 N moves from the surface of earth at a height half of the radius of earth, then gravitational force exerted on it will be

1. 36 N
2. 32 N
3. 144 N
4. 50 N