The gravitational force of attraction between two bodies of masses 60 kg and 40 kg separated by a distance 10 m is : (where G = 6.7 x 10^-11 Nm²kg^-2 )

1. 1.60 x 10^-9 N
2. 2.8 x 10^-11 N
3. 1.0 x 10^-11 N
4. 1.6 x 10^-11 N

The S.I. unit of g is :

1. m s^-1
2. m s^-2
3. cm s^-1
4. cm s^-2

The value of g on a planet depends on :

1. the mass of the planet
2. the radius of the planet
3. both (a) and (b)
4. composition of the planet

A body is projected vertically upward with an initial velocity u. If acceleration due to gravity is g, the time for which it remains in air, is —

1. u/g
2. ug
3. 2u/g
4. u/2g