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Ok I have been going crazy and I think I must be making a simple algebra mistake. Basically in my book I read over an example dealing with a head on collision between 2 balls and the collision is elastic so the kinetic energy intial= final KE. The momentum is also conserved so i can use momentum final=momentum initial. I tried combining these formulas but I always get quadratic. My work is in the image.

The two formulas I am combining are the 1/2m1*vf1^2+ 1/2 m2*vf2^2=1/2m1*vo1^2

and m1*vf1+m2*vf2=m1*vo1

http://img825.imageshack.us/img825/2450/001copys.jpg [Broken]

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the problem just gave 2 balls first one has inital velocity and second one is initially at rest. the book gave the simple formula vf1^2=v01(m1-m2/m1+m2)

THANKS YOU FOR ANY HELP! i have done this wayy too many times and gotten wrong answers.

The answers from book is vf1=-2.62m/s and vf2=2.38m/s

The two formulas I am combining are the 1/2m1*vf1^2+ 1/2 m2*vf2^2=1/2m1*vo1^2

and m1*vf1+m2*vf2=m1*vo1

http://img825.imageshack.us/img825/2450/001copys.jpg [Broken]

Uploaded with ImageShack.us

the problem just gave 2 balls first one has inital velocity and second one is initially at rest. the book gave the simple formula vf1^2=v01(m1-m2/m1+m2)

THANKS YOU FOR ANY HELP! i have done this wayy too many times and gotten wrong answers.

The answers from book is vf1=-2.62m/s and vf2=2.38m/s

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