# Proton moving through a magnetic field

• dprimedx

## Homework Statement

A proton moves perpendicularly to a magnetic field that has a magnitude of 6.48x10-2T. A magnetic force of 7.16x10-14N is acting on it. If the proton moves a total distance of 0.500m in the magnetic field, how long does it take for the proton to move across the magnetic field? If the magnetic force is directed north and the magnetic field is directed upward, what was the proton's velocity?

## Homework Equations

F=ma
F= BIL
(Those are what the teacher gave us. He said that's all we need.)
V2 = 2a*change in x (sorry, not sure how to make a delta)

## The Attempt at a Solution

After chugging through those equations, I got a time of 1.528x10-7. I'm not sure how to figure how the second part - the directions - but I think it has something to do with the right hand rule. Am I right? (For both the time and directions?)

Thanks for taking the time to at least read this over. Please pardon the lack of LaTeX, I'm not too familiar with it. If you can help at all, even point me in the right direction, I'll appreciate it greatly.

I think you want to consider the Lorentz force on the proton.

F = q*v X B

You know everything but the v which you can solve for. Then from there

t = x / v

Could you show us the work you did to get the time?

Edit: Nevermind, I was too slow at asking, LowlyPion showed the correct work for solving the time :)

I think you want to consider the Lorentz force on the proton.

F = q*v X B

You know everything but the v which you can solve for. Then from there

t = x / v

We've never done that in class - this is just a scholar's high school non-calculus physics class. I have no idea what the Lorentz force is. Could you explain some?

The Lorentz expression in vector notation is expressed as the cross product.

F = q*v X B

This is where you need your right hand rule.

Thanks for the help, everyone. I figured it out with F=Bqv. Much more simple than I thought it would be. Again, thanks.