- #1

mewon

- 5

- 0

## Homework Statement

What is the escape speed for an electron initially at rest on the surface of a sphere with a radius of 1.0 cm and a uniformly distrubted charge of 1.6 X 10^-15 C? That is, what initial speed must the electron have in order to reach an infinite distance from the sphere and have zero kinetic energy when it gets there?

## Homework Equations

E = spherical surface with q charge: 1/2Eo (q/r)

U = -W

eV = Winfinity->A

Ke = 1/2(mv^2)

f=ma=qE

Vf + Vi + Ui + Uf = 0

## The Attempt at a Solution

I've played with all these relevant equations and tried to massage the numbers, but I'm pretty off.

I know that we have equilibrium while the electron is on the charged sphere surface. We have Vi. When we reach point infinite distance from sphere we have Vf...why does it have zero kinetic energy when it gets there if Kinetic energy is different from Work? Doesn't that mean it has no mass and no velocity?

The last relevant equation gives me ideas that I should be working in two parallel equations.

Thanks in advance. It's really great to read through all the forums in here and see some of the fun challenges that lie ahead in Physics - harmonic oscillations, divergence/convergence.