Calculate the gravitational potential energy of a body of mass `30 kg`, at a height of `4 R` from the surface of Earth, where `R (= 6.4 xx 10^(6) m)` is the radius of the Earth. Mass of the Earth `= 6.0 xx 10^(24) kg, G = 6.67 xx 10^(-11) Nm^(2) kg^(-2)`.

Explanation

Here, `m = 30 kg, M = 6.0 xx 10^(24) kg`
Distance of body from the centre of earth
`r = 4R + R = 5R = 5 xx 6.4 xx 10^(6) = 32.0 xx 10^(6) m`
Gravitational potential energy of body
`= - (GM m)/(r ) = - ((6.67 xx 10^(-11)) xx (6 xx 10^(24)) xx 30)/(32 xx10^(6))`
`= - 3.75 xx 10^(8) J`