The total energy of a free electron moving through empty space is E=1.5mc^2, where m is the mass of the electron and c is the speed of light. What is this electronâ€™s speed?(adsbygoogle = window.adsbygoogle || []).push({});

1. c (the speed of light)

2. 0.7453c

3. 0.8660c

4. 0.9428c

5. 0.9950c

6. 0.9999c

I thought since that Etotal = 1.5mc^2 then....

Etotal = KE = .5mv^2

1.5mc^2 = .5mv^2 and solve for v (masses would cancel which is what I was looking for)

What is wrong about this approach?

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# Speed of Free Electron Moving in Space

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