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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 I am also wondering why setting one ball's velocity to zero wouldn't work? Please help! Thank you and any help is greatly appreciated =D