# Collision and Momentum of Blocks

1. Nov 2, 2015

### Tim Wellens

1. The problem statement, all variables and given/known data
If block A slides with a velocity into block B which is at rest, and after this collision block B ends up with a velocity and block A is stationary after. Block B has a mass of 5m.

Would this type of collision be an elastic collision or inelastic? How do you know?

What would the velocity of block B be after the collision?

2. Relevant equations
M1V1i+M2V2i=M1V1f+M2V2f

3. The attempt at a solution
I
'm pretty sure this is an elastic collision problem because it seems as though the momentum is conserved and transferred from block A to block B.

This is what i did to figure the velocity of block b after the collision-
MVi+5MVi=MVf+5MVf
MVi+0=0+5MVf
MVi=5MVf
Vf=Vi/5

But i'm not sure if this is right or what I could do differently..

2. Nov 2, 2015

### haruspex

Momentum will certainly be conserved, but that does not make it elastic. In an elastic collision KE is conserved.
Can you work out whether KE is conserved?
Yes, although the question statements reads as though you left something out. Should it say "If block A slides with a velocity v into block B...", or somesuch? If so, you should use the same name for the given velocity in the answer.