Two billiard balls each of mass 0.05 kg moving in opposite directions with speed 6 m/s collide and rebound with the same speed. What is the impulse imparted to each ball due to the other?

Ques: Two billiard balls each of mass 0.05 kg moving in opposite directions with speed 6 m/s collide and rebound with the same speed. What is the impulse imparted to each ball due to the other?

Ans: Mass of each ball = 0.05 kg

Initial velocity of each ball = 6 m/s 

Magnitude of the initial momentum of each ball, pi = 0.3 kg m/s

After collision, the balls change their directions of motion without changing the magnitudes of their velocity. 

Final momentum of each ball, p f = –0.3 kg m/s

Impulse imparted to each ball = Change in the momentum of the system

= p f – pi

= –0.3 – 0.3 

= –0.6 kg m/s

The negative sign indicates that the impulses imparted to the balls are opposite in direction.