Question

A boy of mass 50 kg running at 5 m/s jumps on to a 20 kg trolley travelling in the same direction at 1.5 m/s. What is their common velocity?​

Answer 1

Solution :-

Initial total momentum = (50 x 5 + 20 x 1.5 ) kg m/s = 280 kg m/s

Final combined mass = (50 + 20) kg = 70 kg

Let the final velocity of the combined system = V

According to the conservation of linear momentum:

70 V = 280

V = 280 / 70 = 4 m/s