# Repulsion between two pith balls

1. Nov 22, 2004

### Biya

i kinda need help. okay im posting my question:
Two pith balls have a mass of 1.0g and have equal charges. One pith ball is suspended by an insulating thread. The other is attached to a static insulator and is brought close to the suspended ball so that they are 5 cm apart when repulsion occurs. After repulsion, they come to rest such that both are at the same height above ground. The suspended ball is now hanging with the thread forming a 30 degree angle with respect to its former position. Calculate the following:
1-Force of weight of the suspended ball.
2-The force of repulsion between the two.
3-The net charge on each.
I have no idea how to find out the force of repulsion and the net charge. We can find the weight my using the W=mg formula. So i'm confused with that. I need help . Thank God i found this cool forum

Last edited: Nov 22, 2004
2. Nov 22, 2004

### Integral

Staff Emeritus
Start by drawing a force diagram. Since both balls are stationary you forces must all balance.