Question

In a snooker match ball A is hit and it is moving with speed 4 m/s in the x-direction. It goes and hits balls B and C such that after collision ball B moves with velocity 4 m/s at angle $\circ 60$ to x-direction and A comes to rest. Find the velocity of ball C?

• A. $2\hat{i}+2\hat{j}$
• B. $4\hat{i}+4\sqrt{3}\hat{j}$
• C. $2\hat{i}+2\sqrt{3}\hat{j}$
• D. None of these

Answer 1

The correct option is C

$2\hat{i}+2\sqrt{3}\hat{j}$

We can choose these 3 balls as our system as no net external force in x or y direction and apply conservation of momentum in those directions

Solving (I) & (II) we get

$\theta ={60}^{\circ }$

And v = 4 m/s

In unit - vector notation

$vcos{60}^{\circ }\hat{i}+vsin{60}^{\circ }\hat{j}$

$v=2m/s\hat{i}+2\sqrt{3}m/s\hat{j}$