What equal charges would have to be placed on earth and moon to neutralize their gravitational force of attraction ? Given that mass of earth `= 10^25` kg and mass of moon = `10^23 kg`.

A rocket is fired from the earth towards the sun. At what distance from the earth’s centre is the gravitational force on the rocket zero ? Mass of the sun = 2xxl0^30 kg , mass of the earth = 6xxl0^24 kg . Neglect the effect of other planets etc. (orbital radius = 1.5 xx 10^11 m ).

Find the mass of earth (Given the radius of earth R= 6.4 xx 10^6 m) .

Which one is greater-the gravitational force of the earth on 1 kg iron or the force of gravitation applied by 1 kg on earth ?

A body weighs 63 N on the surface of the earth. What is the gravitational force on it due to the earth at a height equal to half the radius of the earth ?

A satellite orbits the earth at a height of 400 km above the surface. How much energy must be expended to rocket the satellite out of the earth’s gravitational influence? Mass of the satellite = 200 kg, mass of the earth = 6.0xxl0^24 kg , radius of the earth = 6.4 xx 10^6 m , G = 6.67 xx 10^11 N m^2kg^2 .