Q.
A simple pendulum is released from $A\ $shown.
If $m$ and $l$ represent the mass of the bob and
Length of the pendulum, the gain kinetic energy
at $B$ is
A) $\frac{mgl}{2}$
B) $\frac{mgl}{\sqrt{2}}$
C) $\frac{\sqrt{3}}{2}mgl$
D) $\frac{2}{\sqrt{3}}mgl$
Explanation
(c) Loss of potential energy in coming from $A$ to $B$
$= mgh$
$= mgl\cos{30{^\circ} = \frac{\sqrt{3}}{2}}\ mgl$
[image:14_image62.emf]
Kinetic energy gained = loss of potential energy
$= \ \frac{\sqrt{3}}{2}\ mgl$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.