# Physics conversion problem ?

J.live
The electron-volt, eV, is a unit of energy (1 eV = 1.602 10^-19 J, 1 MeV = 1.602 x 10^-13 J). Since the unit of momentum is an energy unit divided by a velocity unit, nuclear physicists usually specify momenta of nuclei in units of MeV/c, where c is the speed of light (c = 2.998 108 m/s). In the same units, the mass of a proton (1.673 · 10^−27 kg) is given as 938.3 MeV/c2. If a proton moves with a speed of 18,646 km/s, what is its momentum in units of MeV/c?

The attempt at a solution

I know the rule of the forum is I have to attempt the problem before someone can help me. But, honestly I don't know how to initiate this problem. I have tried but failed.

It will be appreciated if someone can at least show me the procedure if not the answer.

## Answers and Replies

Homework Helper
Gold Member
What are the units of pc, where p is the momentum of the proton?

J.live
What is pc? I don't see any pc in the given problem :/

J.live
bump :/

Homework Helper
Gold Member
What is pc? I don't see any pc in the given problem :/

There is a pc in the problem, you just don't see it yet. Determine the units of this quantity and you should have a strong hint about how to get the answer you're looking for.

Staff Emeritus