Question

A man weighing 60kg runs along the rails with a velocity of 18km/h and jumps into a car of mass 1 quintal standing on the rails. Calculate the velocity with which the car will start travelling along the rails.

(a) 15m/s

(b) 3.3m/s

(c) 1.88m/s

(d) 5m/s

Answer 1

Correct option is (c) 1.88m/s

For explanation: m1 = 60kg, u1 = 18km/h = 5m/s

m2 = 1quintal = 100kg, u2 = 0, v = ?

By conservation of linear momentum, (m1+m2)v = m1 u1+m2 u2

v = (60×5)/160 = 1.88m/s.