physics
posted by Jen on .
Two identical small insulating balls are suspended by separate 0.17 m threads that are attached to a common point on the ceiling. Each ball has a mass of 7.40 104 kg. Initially the balls are uncharged and hang straight down. They are then given identical positive charges and, as a result, spread apart with an angle of 26° between the threads.
What is the charge on each ball?
What is the tension in the threads?

13 degrees from vertical
T = tension
T cos 13 = m g
so T = m g/cos 13
solve for T
T sin 13 = horizontal force
so
T sin 13= k Q^2/(2*.17* sin 13)^2