Relativistic Kinetic Energy & Gamma

[mhrokosz]

Homework Statement

(7.) If its kinetic energy is 3000 MeV, find its speed as a multiple of c. In this case you cannot use the nonrelativistic approximation.

m=4000 MeV/c^2 (rest energy=4000MeV)
^from previous problem, of which this one is a continuation

Homework Equations

KE=(γ-1)mc^2

The Attempt at a Solution

since v is only present in the gamma equation, I figured I'd have to solve for it there? The negatives in the ensuing algebra don't seem right.

(KE/MC^2)+1=1/(√1-(v2/c2))

 

[jbsteele]

3000/4000c^2 +1 = 1/(√1-(v2/c2)) 3/4 +1=1/(√1-(v2/c2)) 4/4=1/(√1-(v2/c2)) 1=1/(√1-(v2/c2)) 1-(v2/c2)=1 v2/c2=0 v=0? I don't think that's right though.