# Homework Help: EV unit conversions

1. Feb 21, 2004

### gnome

I'm having a hard time getting used to expressing quantities in electron-volt equivalent units.

Masses and energies expressed as MeV/c2 are confusing, but manageable.

But I seem to have a complete mental block over momentum as MeV/c. It's easy enough to look at a table & see that 1 MeV/c = 5.344 x 10-22 kg-m/s, but could someone please walk me (or drag me ) through the derivation of that conversion?

2. Feb 23, 2004

### Tom Mattson

Staff Emeritus
The units of momentum are those of energy over speed.

(1 Joule/m/s)=(1 J*s/m)*(1eV/1.6*10-19J)*(3*108(m/s)/1c)

Cancel the units, crunch the numbers, and you'll have it.