A body of mass 200 kg is at rest on the earth's surface. (i) Find its gravitational potential energy . (ii) Find the kinetic energy to be provided to the body to make it free from the gravitational influence of the earth. (g = 9.8 m`//s^(2) , R = 6400 km`)

Explanation

Data : m = 200 kg , g = 9.8 m`//s^(2) , R = 6400 km =6.4 xx 10^(6) m`
(i) The gravitational potential of the body
`- ( GMm)/R = - mgR ( therefore g = (GM)/R^(2))`
` = - 200 kg xx 9.8 m//s^(2) xx 6.4 xx 10^(6) m= - 1.2544 xx 10^(10) J`
(ii) To make the body free from the gravitational influence of the earth , it should be provided kinetic energy equal to ` 1.2544 xx 10^(10)` J