Question

Two billiard balls A and B, each of mass 50 g and moving in opposite directions with speed of 5 ms^–1 each, collide and rebound with the same speed. If the collision lasts for 10^–3 s, which of the following statements are true?

1. The impulse imparted to each ball is 0.25 kg ms^–1 and the force on each ball is 250 N.
2. The impulse imparted to each ball is 0.25 kg ms^–1 and the force exerted on each ball is 25 × 10^–5 N.
3. The impulse imparted to each ball is 0.5 Ns.
4. The impulse and the force on each ball are equal in magnitude and opposite in direction.

Answer 1

c and d

Explanation:

We are given that, m = 0.05 kg and v = 5 m/s

Hence we have initial momentum of each ball p = mv = 0.05 × 5 = 0.25 kg ms^–1

After the collision, both balls will move in opposite directions

Hence, we have the final momentum of each ball p' = – mv = – 0.05 × 5 = – 0.25 kg ms^–1

Now the impulse is the change in momentum,

Hence, I = p' – p = – 0.25 – 0.25 = – 0.5 kg ms^–1.