Question

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

Answer 1

Explanation:

m1 = 50 kg

v1 = 5 m/s

m2 = 20 kg

v2 = 1.5 m/s

v3 = final velocity

Formula:

m1v1 + m2v2 = (m1 + m2) x v3

We need to find v3

v3 = (m1v1 + m2v2) / (m1 + m2)

= (50x5 + 20x1.5) / (50 + 20)

= 280 / 70

= 4 m/s

The final velocity is 4 m/s