# Homework Help: Solving for velocity in relativistic momentum

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1. Feb 6, 2016

### JWood521

1. The problem statement, all variables and given/known data
the relativistic momentum of an electron is 1.6 times larger than the value computed non-relativistically. What is the speed of the electron.

2. Relevant equations
Relativistic momentum
p=mv/√1-v2/c2

3. The attempt at a solution
Moving most of the equation around is fairly easy, but I'm getting stuck with v2 on both sides of the equation, so they appear to cancel out. The equation I've come up with to solve for velocity in relativistic momentum is:

v2=c2(1-((m2v2)/P2)

How to I move the v2 over to the left side without canceling out the velocities?

The algebra behind manipulating the relativity equations (due to the gamma adjustment) has been the one thing I've struggled with in the relativity topic. An explanation of the math concept behind solving for velocity in this equation would be EXTREMELY helpful!

2. Feb 6, 2016

### Ray Vickson

Write down the actual equation you have to solve in order to finish the problem. Don't worry yet about how to solve the equation; just write it down to start with.

3. Feb 6, 2016

### Staff: Mentor

What is P in that equation?

It would help if you would show your steps.