Velocity and momemtum of 10 Mev Electron

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Homework Statement



Find the velocit y and momentum of an electron (rest mass of 0.511MeV) with a
kinet ic energy of 10.0 MeV.

The Attempt at a Solution



The momentum I calculate using sqrt(2KEm) is giving me a V larger than the speed of light. This can't be true.

If I try
Rest E + KE = sqrt (m2c4 - p2c2) it gives me a negative root.
 
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Nevermind, I figured it out.
 
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