- #1

- 26

- 0

## Homework Statement

A resting electron was sped up to 0.5 of the speed of light. Find:

A. relativistic mass of the electron,

B. total energy of the electron,

C. kinetic energy of the electron.

## Homework Equations

K = mv^2/2

E=mc^2

## The Attempt at a Solution

Let’s first find the kinetic energy:

K = m*v^2/2

K = (9.1*10^-31*0.25*9*10^16)/2 = 1.02375*10^-14 J

Now we should find relativistic mass using E=mc^2.

m(rel) = E/c^2 = (1.02375*10^-14)/(9*10^16) = 1.1375*10^-31 kg

Total energy must be = m(rest)*c^2

Then E(total) = 9.1*10^-31*9*10^16 = 8.19*10^-14 J

Is this solution correct?

And I suppose potential energy = 8.19*10^-14 - 1.02375*10^-14 = 7.16625*10^-14 ? :)

Last edited: