# Two electrons, one moving towards the other.

## Homework Statement

Two electrons, one moving towards the other that is in a fixed position. Determine the final speed of the mobile electron when it is far away from the fixed one.

Initial Velocity 10^5m/s directly at the fixed electron.
Mass electron = 9 x 10^-31kg
distance between them 10^-8m

## Homework Equations

W=Fd
Work initial = Work final

## The Attempt at a Solution

I first attempted to find the distance r between the two electrons, when KE final is zero. I set Wfinal = Winitial and solved for r. r = 5.8 x 10^-8, which is larger than the original d= 10^-8.

The Force on q at r= 10^-8m is also much larger than the KE of the moving electron. Does Electric Field Force > KE mean that the particle should instantly reverse directions and be repelled away?

If my assumption is correct I can then find the final velocity by equating Fd = KE and solving for v. Where d = "far away" = 1m

Thanks!

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gneill
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