Q. A body falls freely under gravity. Its speed is $v$ when it has lost an amount $U$ of the gravitational energy. Then its mass is
A) $\frac{Ug}{v^{2}}$
B) $\frac{U^{2}}{g}$
C) $\frac{2U}{v^{2}}$
D) $2Ugv^{2}$
Explanation
(c) $U =$ Loss in gravitational energy = gain in K.E.
So, $U = \frac{1}{2}mv^{2} \Rightarrow m = \frac{2U}{v^{2}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.