Couple of Electrostatics Concepts

[epix]

Momentum, Speed, Acceleration

1. Which of these is constant when a charged particle is placed in a uniform electric field?

http://img638.imageshack.us/i/lol025.jpg/

2. If an electron was placed at P, would it accelerate toward D or E?
If you can't see, the bottom left charge is +4q and the bottom left is -8q.

http://img534.imageshack.us/i/lol024.jpg/
3.Where on the line will the electric potential be zero and where will the electric field be zero?
If you can't see too well, the charge on the left is -2q, the one on the right is q and each section is labeled I, II, III respectively.

4. And the last one!
http://img339.imageshack.us/i/lol026.jpg/

I'm looking at these formulas:
W=q▲V
V=Ue/q = kQ/r
Ue = KQq/r

I'm not sure how I should usem though.

If anyone can help me with any of these I'd really appreciate it, thanks!

 

[jbsteele]

1. The speed of the particle will remain constant when a charged particle is placed in a uniform electric field.2. The electron would accelerate toward D since it has the higher positive charge.3. The electric potential will be zero at point I and the electric field will be zero at point II.4. Using the formulas given, you can calculate the work done by the electric force (W) as work is equal to the change in potential energy (q ΔV). You can also calculate the electric potential (V) which is equal to the electrostatic potential energy (Ue) divided by the charge (q). Finally, you can calculate the electrostatic potential energy (Ue) which is equal to the product of the electrostatic constant (K), the charge of an object (Q), and the charge of a second object (q) divided by the distance between them (r).