Hello Aspirant,

Answer :

2

Solution :

Consider first collision b/wb/w Mand4MMand4M on the right, the velocities after collision are
VM=−35u,V4M=25uVM=-35u,V4M=25u
Particle of mass MM will move to the left and collide with 4M4M . The velocities after collision are
VM=(35)2u,V4M=25×35uVM=(35)2u,V4M=25×35u
So in all there are two collision.

Hope it helps!