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 10-4 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.

Question

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  10-4 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?

Damon · Answer

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