Elastic collision between two moving objects

[captainmustard]

Homework Statement

A 0.2 kg block, moving at 6 m/s, is catching up and colliding elastically with a 0.6 kg block that is moving along the same line and in the same direction. Find the velocities of the ball after this one-dimensional collision.

Homework Equations

Conservation of momentum, conservation of energy

The Attempt at a Solution

First, I figured the momentum and kinetic energy would be conserved so I setup a couple of equations:

m1v1i + m2v2i = m1v1f + m2v2f
and
m1v1i^2 + m2v2i^2 = m1v1f^2 + m2v2f^2

At this point, I realize I have 3 unknowns (v2i, v1f and v2f) and I simply don't know what I can even do with this information. Any ideas at all would be helpful.

 

[TSny]

Hi, captainmustard. Welcome to PF!

You are right. There is not enough information to answer the question. You have set up the correct equations.

 

[captainmustard]

Thank you for the response. I thought I was going crazy for a moment there. Would this be possible if it were a completely inelastic collision? I would imagine it would involve some tedious algebra if so.

 

[ehild]

No, you need the initial velocity of the 0.6 kg ball, too.

ehild