Question

A particle of mass 2m moving with velocity v strikes a stationary particle of mass 3m sticks to it. The speed of the system will be

Answer 1

We can solve this problem by using law of conservation of linear momentum

Answer 2

u1 = speed of ball with mass 2m = v m/s

u2 = speed of ball with mass 3m  = 0 m/s

u3 = total velocity of the system

according to the law of conservation of linea momentum ,

m1u1 + m2u2 = m3u3

2v + 0 = ( m1 + m2 ) u3

2v = ( 2 +3 ) u3

2v / 5 = u3

0.4 v = u3

so , the total velocity of the system is 0.4 v