Question

Calculate the speed of an electron which has kinetic energy of 2 mev.(rest mass of electron is 0.511 mev).

Answer 1

k.e.=2mev
rest mass=0.511mev
total energy=k.e.+rest mass
e=2.511mev
by the equation e=mc^2
square root of e/m=c
square root of 2.511/9.10938356×10^-31=c
square root of 0.2756498267×10^-31=c
1.66027054E-16m/s=c