Hello. I've uploaded the question onto pictures and linked them. I hope this method of asking a question works.(adsbygoogle = window.adsbygoogle || []).push({});

I'm trying to find the mass of the ball, but I get the square root of a negative number. Can someone take a look to see if I'm doing this problem correctly?

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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# Homework Help: Conservation of Four-Momentum

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