Question

A pendulum has a mass of 2.35 kg. If the pendulum swings back and forth 110 times in 90.0 seconds, what is the length of the pendulum

Answer 1

$T=2\pi\sqrt{\frac lg},$

$T=\frac tn,$

$l=\frac{gt^2}{4\pi^2n^2}=16.6~cm.$