Question

Two balls are on a frictionless horizontal tabletop. Ball x initially moves at 10 meters per second, as shown in Figure 1 above. It then collides elastically with identical ball Y which is initially at rest. After the collision, ball x moves at 6 meters per second along a path at 53 degrees to its original direction, as shown in Figure 2 above, Which of the following diagrams best represents the motion of ball Y after the collision?

Answer 1

Answer:

Option (B)

Explanation:

We know that without any external force velocity of center of mass must be same. So, velocity of Center of Mass of balls must be in same direction as that of Ball X.

So, velocity of center of mass perpendicular to the direction of initial must be zero.

As given in question after collision ball X moves with velocity 6 mps with an angle 53° with its initial path. So velocity of ball X in perpendicular direction is $\frac{24}{5}$

Hence the perpendicular component of ball Y must be $\frac{24}{5}$

By checking We get that option (B) satisfy the condition.