# Speed of electron

1. Feb 23, 2008

### tony873004

** Edit: Nevermind. I figured it out using the Work Energy theorem.

An electron is released from rest 1.0 cim above a uniformly charged infinite plane with a charge density of 10-9C/m2. What is the speed of the electron when it hits the plane?

my attempt:
Potential energy when it is released= kinetic energy when it hits.

kqQ/r = 0.5 mv2

isolate v:

$$v = \sqrt {\frac{{2kqQ}}{{m \cdot r}}}$$

This would work if I was given 2 point charges, but how do I do this with a charge density and a point charge?
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

Last edited: Feb 23, 2008