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## Homework Statement

A 0.06kg tennis ball, moving with a speed of 2.50 m/s, collides head-on with a 0.09kg ball initially moving away from it at a speed of 1.15m/s.Assuming a perfectly elastic collision,what are the speed and direction of each ball after the collision?

## Homework Equations

Ok well I know P=mv

Also my teacher gave me the equation: V1-V2=-(V1prime-V2prime)

and kinetic energy along with momentum is conserved.

## The Attempt at a Solution

What I tried was setting the second ball's velocity to 0 m/s meaning the first ball would have a velocity of 1.35 m/s instead of the original 2.50m/s and I used the equation V1prime=(m1-m2)/(m1+m2) x (v1), however the answer didn't come out. I have no idea how to start this problem and Im also wondering why setting one ball's velocity to zero wouldn't work? Please help!! Thank you and any help is greatly appreciated =D