# Homework Help: Work-energy principle

1. Aug 6, 2009

### XTEND

1. The problem statement, all variables and given/known data
2 large metal sheets are seperated by a potential of 40 volts by a vaccum. When the proton particle (mass 1.67x10e-27 kg)is released close to the (+) sheet it moves closer to the (-) sheet by way of electric field. What's the KE right before the proton smacks the other sheet? And what's the velocity of before striking the (-) sheet?

2. Relevant equations

KE=>q*v and EK=mv^2/2

3. The attempt at a solution

KE= 1.6x10e-19(40)=6.4x10e-18

v= ?

2. Aug 6, 2009

### jgens

What's the formula for the kinetic energy of an object (in terms of the object's velocity)?

3. Aug 6, 2009

### XTEND

Can anyone help me with this?

I think the velocity is 87548 m/s. Is this correct?

4. Aug 6, 2009

5. Aug 6, 2009

### XTEND

what about the first part for KE?

6. Aug 7, 2009

### ideasrule

If that isn't correct, you wouldn't have gotten the right answer for v. So yes, KE=qV, and your calculation is right as well.