Question

A small ball with a mass of 0.6 kg and a velocity of 12 m/smetre per second hits another ball with the same mass. The first ball stops moving, and the second ball then moves forward and hits a third ball with a mass of 0.2 kgkilo gram. If the system is closed, what is the velocity of the third ball? (1 point)
Responses

1.44 m/s2
1.44 meter per second squared

30 m/s2
30 meter per second squared

36 m/s2
36 meter per second squared

4 m/s2
4 meter per second squared

Answer 1

Initial momentum = 0.6 kg × 12 m/s = 7.2 kg·m/s.
If the first two balls end up stopped and the system is closed, all momentum goes to the third ball: m3 v3 = 7.2, so v3 = 7.2 / 0.2 = 36 m/s.

(Option: 36 m/s — the choices' units m/s^2 are incorrect.)