# Elastic collision

1. Two objects collide M1 = 1kg M2 = 3kg V1 = 2m/s V2 = -4 m/s V1' = ? V2' =?

2. PEi = PEf m1v1 + m2v2 = m1V1' + m2v2' KEi=KEf same as (1/2)(PE^2)/m

3. PEi = PEf ----> 2 - 12 = -10 ---> v2' = (-10 - v1')/3
KEi = KEf ----> 4 + 48 = 52 ----> 156 3Vi^2' + V1^2' + 20v' +100

4. V1' = - 7 V2' = -1
KEi = 2J + 24J = 26J KEf = 24.5J + 1.5J = 26J

The real Question: I tried to manipulate the problem with algebra but to no ends. So here is my question, how do you obtain V1 or V2 with (not V1' or V2') Can you obtain your numbers if lets say you have

1. Two objects collide M1 = 1kg M2 = ? V1 = ? V2 = -4 m/s V1' = -7 V2' =? What format would you use to solve this. I tride using the same equations but I can't seem to manipulate the algebra to do what I want. I keep getting either really small or really large numbers.[/

## The Attempt at a Solution

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I don't understand, you have 3 variables and two equations? Also your equations are almost unreadable.

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I just zipped by to show that i can do it and have gotten the answer. Was wondering if there was a way to obtain an answer if the variables where miss matched . so instead of the equation asking for V1' and V2' (like stated above) it would be asking for M2, V1 and V2' =?

You can do it? Show me please!

I think it's impossible when you have only two equations for three variables. (Unless you can eliminate two variables at once somehow...)