Question

A 1.00 g mass hangs by a string next to an identical stationary mass. When both masses are given identical positive charges, the hanging charge swings out 3.00 cm from the vertical so that its string makes an angle of 30.0 degrees with the vertical. Find the magnitude of the charge.

Horizontal force= kqq/.03^2
vertical force=mg

tan30= horizontalforce/verticalforce

solve this for q