- #1

ploppers

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## Homework Statement

A ping pong ball of mass 3*10^-4 kg is hanging from a light thread 1 m between 2 vertical parallel plates 10 cm apart. When the potential difference across the plate is 420V, the ball comes to equilibrium 1 cm from one side of the original position. What is the tension of the string, charge and electric force on the ball?

## Homework Equations

E = V/r

F = Eq

## The Attempt at a Solution

found the force in the horizontal is 2.92*10^-4 through spliting up the force of gravity. Tension force is the same as it would be going straight down so I found the angle with 1 cm and 10cm and cos the force to get the horizontal force. That would be the force the system acts on it.

F = Eq

2.92*10^-4 = Vq/r

2.92*10^-4 * r / v = q

this is where I get my problem...is the potential energy conssistant throughout the system like the force? If it is then I can get to an answer, but if it isn't, what do I do? If you can;'t understand what I wrote i apologize, I'm very confused and frusterated