Solution to problems – class 9 physics – Set 1 Q 54

Last updated on January 2nd, 2020 at 07:57 am

Problem Statement

54) 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?

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

Go back to the 101 problems set (class 9)

Problems Set – grade 9