- #1
fluidistic
Gold Member
- 3,923
- 260
Homework Statement
Calculate the kinetic energy of an electron whose momentum is 2MeV/c.
Homework Equations
[tex]P=\gamma m_0 v =mv[/tex].
[tex]E_K=(m-m_0)c^2[/tex].
The Attempt at a Solution
I'm told that [tex]\gamma m_0 v=\frac{2MeV}{c}[/tex].
If only I had the mass at rest of the electron (it isn't given in the problem), I could calculate its velocity with the first formula I gave. Then I could calculate its mass (not its rest mass, its apparent mass or whatever it's called). And then I could apply the third formula and this would solve the problem. Am I right?
So, should I look for the electron's rest mass in some book? Is there a missing data, or can I solve the problem without this info?