Two objects, one of mass 3kg moving at 2m/s, the other of mass 5kg and speed of 2m/s move towards each other and collide in a head on collision. If the collision is perfectly inelastic, find the speed of the objects after the collision.

Answer 1

call + x direction the initial direction of the first (3 kg) mass

initial momentum = 3*2 -5*2 =6-10 = -4

final momentum also -4, mass = 8

8 * v = -4
v = -1/2

Answer 2

Since its perfectly inelastic the final velocity is negated since KE in the collision is maximum

M1V1-M2V2=(M1+M2)-Vc :Vc as final velocity

Substitute value
(3*2)-(5*2)=(5+3)(-Vc)
-4=-8Vc
Vc=0.5m/s