A body of mass m is placed on the earth's surface. It is then taken from the earth's surface to a height ` = 3R`, then the change in gravitational potential energy is

Options

A. `"mgR"/4`
B. `2/3mgR`
C. `3/4mgR`
D. `"mgR"/2`

Answer

C

Explanation

Change in G.P.E.=final energy - initial energy
`=-"GMm"/"4R"+"GMm"/R="GMm"/R[1-1/4]`
`=3/4 "GMm"/R=3/4"GM"/R^2 mR=3/4 gmR`