The gravitational potential energy of a body of mass m at the earth's surface is `mgR_e` . Its gravitational potential energy at a height `R_e` from the earth's surface will be .....
(Here `R_e` is the radius of earth)

Options

A. `-2 mg R_e`
B. `2 mg R_e`
C. `1/2 mg R_e`
D. `-1/2 mg R_e`

Answer

D

Explanation

`implies DeltaU = U_(2) - U_1 = (mgh)/(1+(h)/(R_e) ) = (mgh)/(1+R_e/R_e) = (mgR_e)/2`
`:. U_2 - (-mg R_e) = (mgR_e)/2`
`:. U_2 =-1/2 mg R_e`