Q. A particle is projected from a point $A$ with velocity $u\sqrt{2}$ at an angle of $45{^\circ}$ with horizontal as shown in figure. It strikes the plane $BC$ at right angles. The velocity of the particle at the time of collision is

A) $\frac{\sqrt{3u}}{2}$
B) $\frac{u}{2}$
C) $\frac{2u}{\sqrt{3}}$
D) $u$
Explanation

(c) Let $v$ be the velocity at the time of collision
[image:4_image120.emf]
Then, $u\sqrt{2}\cos{45{^\circ}} = v\sin{60{^\circ}}$
$\left( u\sqrt{2} \right)\left( \frac{1}{\sqrt{2}} \right) = \frac{\sqrt{3}v}{2}\ \ \ \therefore v\text{=}\frac{2}{\sqrt{3}}u\ $

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.