Question

The swinging pendulum has a period of 4.5 s, find the length of a swinging pendulum.

Answer 1

By the definition of the period of the pendulum, we have:

$$T=2\pi\sqrt{\dfrac{L}{g}},$$ $$L=\dfrac{T^2g}{4\pi^2}=\dfrac{(4.5\ s)^2\cdot 9.8\ \dfrac{m}{s^2}}{4\pi^2}=5.03\ m.$$