The length of a simple pendulum is 0.58 m, the pendulum bob has a mass of 285 g, and it is released at an angle of 16 degrees to the vertical.

Question

With what frequency does it oscillate?

Answer 1

The period of a simple pendulum of length L with small amplitudes is
T=2π√(L/g)
Frequency is the reciprocal of period, T.

For small amplitudes, it is (approximately) not dependent on the mass nor the amplitude (angle).

For higher amplitudes, or greater accuracy, the following series expansion can be used:
T=2π√(L/g)*(1+θ²/16+11θ^4/3072+...)
which turns out to be:
1.5353 s. instead of 1.5278 s. using the simple formula.