A particle of mass `1 kg` is kept on the surface of a uniform sphere of mass `20 kg` and radius `1.0 m`. Find the work to be done against the gravitational force between them to take the particle away from the sphere.

Answer

A, C, D

Explanation

Potential at the surface of sphere,
`V = - (GM)/(R)`
`= - ((6.67 xx 10^(-11))(20))/(1) J//kg`
`= - 1.334 xx 10^(-9) J//kg`
i.e.`1.334 xx 10^(-9) J` work is obtained to bring a mass of `1 kg` from infinity to the surface of sphere. Hence, the same amount of work will have to be done to take the particle away the surface of sphere. Thus,
`W = 1.334 xx 10^(-9) J`