# Homework Help: Electric Potenial

1. Sep 8, 2007

### Winzer

1. The problem statement, all variables and given/known data
The potential difference between two parallel plates is 529 V. An alpha particle with mass of 6.64 kg and charge of 3.20 C is released from rest near the positive plate. What is the kinetic energy of the alpha particle when it reaches the other plate? The distance between the plates is 19.4 cm.

2. Relevant equations
$$U_{initial}=K_{Final}$$
$$U=q_{0}E\DeltaR$$
3. The attempt at a solution
So I am trying to find E now so I can plug that in for U. E=V/distance right? so
$$E= 1058/.194$$?

2. Sep 8, 2007

### learningphysics

You can calculate the electric potential energy immediately. You know q, you know V...

the question is do you need to consider gravitational potential energy for this problem... are the capacitor plates up and down, or side to side?

Last edited: Sep 8, 2007
3. Sep 8, 2007

### Winzer

No, it is simply taking into account the electric potenial energy, no gravity included in the problem.
U=qEr(distance) so don't I need to calculate E?

4. Sep 8, 2007

### learningphysics

You already know V. So U = qV.

5. Sep 8, 2007

### Winzer

V being the potenial difference between the two plate -> 529V correct?

6. Sep 8, 2007

yeah.

7. Sep 8, 2007

### Winzer

ok I got it thanks

8. Sep 8, 2007

### learningphysics

no prob.

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