A simple pendulum of length (1.0m) and mass (5.0*10^-3 kg) is placed in a uniform electric field that is directed vertically upward. The bob has a charge (-8*10^-6 C). The period of the pendulum is (1.2 s). What are the magnitude and direction of the electric field?
The Attempt at a Solution
I'm assuming the question was just being redundant since it provided the direction. Lacking a great deal of knowledge about pendulums, I at first assumed that g in the period equation could be replaced by a generic acceleration, then using the fact that the net vertical force (ignoring tension since if g were the net acceleration under regular circumstances, it would also ignore tension) is equal to the sum of gravity and coulomb force, go through a bunch of algebra to solve for the magnitude of E. I don't know if that's correct...
Otherwise, I'd imagine writing out some kind of DE would make it very complex. I could just use a few hints as to what I should do, or maybe some kind of primer on pendulums in general. Thank you very much.