# Homework Help: Electricity Question

1. Jan 11, 2010

### DR13

1. The problem statement, all variables and given/known data

Protons from a Van de Graaff accelerator are released from rest at a potential of 20MV and travel through a vacuum to a region of 0 potential.
Charge of electron is 1.6x10^-19C and mass of electron is 1.67x10^-27kg
Find the final speed of the 5MeV protons
Answer in units of m/s

2. Relevant equations

eV=U=-.5mv^2
maybe some others. im not sure

3. The attempt at a solution

To be honest I have no idea where to even start. Im not sure why they give me info on electrons then ask about protons. I just need a starting point

Thanks for any help

2. Jan 12, 2010

### ideasrule

I think they simply screwed up and meant to give you the data on protons. It's also interesting why travelling through a 20MV potential difference would give the protons 5MeV. Shouldn't it be 20MeV?

3. Jan 12, 2010

### DR13

Yeah i talked to my teacher to day and she said it was a screw up.
Thanks though