What is the final velocity in the following scenario?A body of mass 16 kg travelling to the right at 5 m/s collides with a body of mass 4 kg...

In a perfectly inelastic
collision:

M1*v1 + M2*v2 = (M1 +
M2)*vf

Here M1 and M2 are the masses of the bodies
colliding, v1 and v2 are their initial velocity and vf is their final
velocity.

Now, in the problem it is given that the body of
mass 16 kg is travelling at 5 m/s towards the right. It collides with a body of mass 4
kg travelling at 5 m/s towards the rest.

Therefore we can
use

M1*v1 + M2*v2 = (M1 +
M2)*vf

=> vf = (M1*v1 + M2*v2)/(M1 +
M2)

=> vf = (16*5 -
4*5)/20

=> vf =
60/20

=> vf = 3
m/s

The final body made up of the bodies that
collided with each other moves at 3 m/s towards the
right.