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how do simple pendulum work and how its time is calculated?

A simple pendulum consists of a weight suspended on a string or wire. If the pendulum weight or bob is pulled to a relatively small angle from the vertical and let go, it will swing back and forth at a regular period and frequency.

There are equations available to calculate the period and frequency as a function of the length of the wire and the acceleration due to gravity. The weight of the bob is not a factor in the equations.

Although damping effects from air resistance and friction are a factor, they are considered negligible for the basic equations concerning the frequency of the the pendulum, as well as the speed of the bob.

The period of the motion for a pendulum is how long it takes to swing back-and-forth, measured in seconds. Period is designated as T.

The frequency of a pendulum is how many back-and-forth swings there are in a second, measured in hertz. Frequency is usually designated as f.

The period T is the reciprocal of the frequency. T = 1/f and f = 1/T.