- #1
Alena Selone
- 12
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Homework Statement
An electron is accelerated to a speed that is 99 percent the speed of light, and is moving through a 2-km-long tunnel. The rest mass of the electron is 9.11*10^-31 kg. What is the mass of the electron at this speed?
c= speed of light
Homework Equations
t= (tsubscript(o))/ root(1-(v^2/c^2)
L= Lsubscript(o)* root(1-0)= Lsubscript(o)
p= (mv)/ root(1-0) = mv
KE= ((mc^2)/ root(1-(v^2/c^2))-mc^2
The Attempt at a Solution
I tried plugging the rest mass into the last equation on the top which gives me 9.11*10^-31/ root(1-((.99c)^2/c^2
which calculates out to
9.11*10^-31/ root(1-.9801)
9.11*10^-31/root(0.0199)
9.11*10^-31/0.14106736
=6.458*10^-30
I'm unsure if this is correct. It's listed as one of the answers but I don't know if I used the correct equation, so the fact that it's listed as an answer could be a trick. I also don't know how the 2km long tunnel plays into the equation. Please help!