Q. The gravitational potential energy of a body of mass $m$ at a distance $r$ from the centre of the earth is $U$. What is the weight of the body at this distance?
A) $U$
B) $Ur$
C) $\frac{U}{r}$
D) $\frac{U}{2r}$
Explanation
(c) $Gravitational\ potential\ energy,\ U = \frac{GMm}{r}$
$or\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ U = \frac{GMm}{r^{2}} \times r$
$or\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ U = g \times mr$
$or\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ U = (mg)r$
$or\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ mg = \frac{U}{r}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.