# Electric Forces between charges

1.

Hanging from threads are two charged balls made of pith (a very light, spongy material that comes from inside the stems of certain plants). The balls each have a mass of 0.100 g and a charge of the same magnitude q and are attracted toward each other, as shown in the figure below. (Take θ = 18.9° and r = 1.82 cm.)

Question: What is the magnitude of the electric force?

F = k (q x q/r^2)