The kinetic energy needed to project a body of mass `m` from the earth surface (radius R) to infinity is

Options

A. `(mgR)/(2)`
B. `2mgR`
C. `mgR`
D. `(mgR)/(2)`

Answer

C

Explanation

The kinetic energy needed to project a body of mass m from the earth surface to infinity is given by
`KE=(1)/(2)mv_(e)^(2)=(1)/(2)m 2Rg`
`(because "Escape velociy", v_(e)=sqrt(2Rg)rArrv_(e)^(2)=2Rg)`
`rArr KE = mRg`