Question

The increase in gravitational potential energy of an object of mass $m$ raised from the surface of Earth to a height equal to radius $R$ of Earth is -

• A. $mgR$
• B. $\frac{m g R}{2}$
• C. $\frac{m g R}{3}$
• D. $\frac{m g R}{4}$

Answer 1

Answer: (B)

Increase in potential energy
$=\frac{- G M m}{2 R}-\left(\frac{- G M m}{R}\right)=\frac{G m M}{2 R}=\frac{G M}{R^{2}}\times \frac{m R}{2}$
$=g \, \times \, \frac{1}{2}mR=\frac{1}{2}mgR$