What is the energy required to launch a `m` kg satellite from earth's surface in a circular orbit at an altitude of 7R ? (R = radius of the earth)

Options

A. `(12)/(13)mgR`
B. `mgR`
C. `(15)/(16)mgR`
D. `(1)/(9)mgR`

Answer

C

Explanation

Energy of satellite - energy of satellite on surface of earth
`=-(GMm)/(2(8R))-[-(GMm)/(R)]=(15)/(16)(GMm)/(r)=(15)/(16)mgR("as" (GM)/(R)=gR)`.