a ball of mass 0.5 kg moving at 10 m/s collides with another ball of equal mass at rest. if the two balls move off together after the impact calculate their common velocity

5 m/s

Explanation:

Here we can see there is no external force acted on a two masses when we consider the motion. If there is no external forces then momentum is conserved.

Initial momentum = Final momentum

0.5 * 10 = 1 * V

V = 5 m/s