What Is the Speed of an Electron With 100000 eV Kinetic Energy?

[RubinLicht]

Homework Statement

what is the speed of an electron with kinetic energy of (a) 100000 eV

Homework Equations

m=m₀/√(1-β²)
K=Δmc²

The Attempt at a Solution

plug first into second equation, isolate v and it eventually comes out to be
v=c(1-(1+K/m₀c²)^-2)
plug in numbers and i get a velocity of 0.9*10⁸ m/s
the answer is 1.6*10⁸ m/s in the textbook.

Note: This isn't a school assignment. I am self studying for physics olympiad, and this is my first encounter with relativity from a mathematical stand point.

 

[TSny]

Your method is correct. So, the mistake must be in plugging in the numbers and evaluating.

 

[RubinLicht]

will try again, thanks