(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\ $