A spherical mass of 20 kg lying on the earth's surface is attracted by another spherical mass of 250 kg with a force equal to the weight of 0.25 mg-wt . The centres of the two masses are 30 cm apart. Calculate the mass of the earth. Radius of earth `=6xx10^6`m.

A sphere of mass 40 kg is alternated by another sphere of mass 15kg with a force of 1/(10) mg -wt . Find the value of G if the separation between the spheres is 20 cm.

The weight of a body on the earth's surface is W. if the radius of the earth becomes double keeping its mass unchanged, what will be the weight of the body ?

The mean orbital radius of the earth around the sun is 1.5xx10^8 km . Calculate the mass of the sun if G=6.67xx10^(-11)N*m^2*kg^(-2) .

If the radius of the earth-shrinks by 2% and its mass remain same, then calculate the value of g on the earth's surface.

An object of mass m is raised up to a small height h above the earth's surface. If the acceleration due to gravity on the earth's surface is g, prove that the weight of the object will decreases by (2mgh)/R with respect to that on the earth's surface . R =radius of the earth.

The velocity of a body of mass 5 kg changes from 20 m/s to 10 /s. calculate the change of momentum of the body.

A satellite of mass 250 kg is orbiting the earth at a height of 500 km above the surface of the earth. How much energy must be expended to rocket the satellite out of the gravitational influence of the earth? Mass of earth = 6 xx 10^24 kg Radius of earth = 6400km.

The earth rotates around the sun in a circular orbit of radius R. Calculate the orbital speed of rotation of the earth around the sun. Also find the time period of rotation. Take the mass of the earth =m, mass of the sum =M.

A rocket is fired vertically with a speed of 5 km *s^(-1) from the earth's surface . How far from the earth does the rocket go before returning to the earth ? Mass of the earth= 6.0xx10^(24)kg , mean radius of the earth= 6.4xx10^6m, G=6.67*10^(-11)N*m^2*kg^(-2) .