# Electric Potential conducting shell

1. Mar 26, 2007

### suspenc3

1. The problem statement, all variables and given/known data
A thin, spherical, conducting shell of radius R is mounted on an isolating support and charged to a potential of $$-V$$. An electron is then fired from point $$P$$ at a distance $$r$$ from the center of the shell. $$(r>>R)$$ with an initial speed $$v_0$$ and directly towards the shell's center. What value of $$v_0$$ is needed for the electron to just reach the shell before reversing direction?

2. Relevant equations
$$\Delta u = \frac{1}{2}mv_0^2$$

3. The attempt at a solution

$$v_0=\sqrt{\frac{2 \Delta u}{m}}$$

Im not sure if this is what I should do, if so, how can I get something for $$\Delta u$$

2. Mar 26, 2007

### robphy

What is the PHYSICS underlying the "relevant equation"?
What does $$\Delta u$$ mean? and how is it related to the "Electric Potential"?

3. Mar 26, 2007

### Nacer

Conservation of Energy Kinetic Energy + Potential Energy = Constant.
Delta U = changes in Potential Energy
= e*V

Regards,

Nacer.

4. Mar 26, 2007

### suspenc3

does "V" have a value?