Question

What type of motion is a pendulum?

Answer 1

Hint:When attempting questions like the one given to us above, keep in mind the different concepts regarding motion and the different types of motion like rotatory motion, oscillating motion, linear motion and reciprocating motion. Remember that all motion types differ in some way or another.

Complete step-by-step solution:
A pendulum is a body which is suspended from a fixed point so that it can swing back and forth under the influence of gravity. In a simple pendulum, the apparatus consists of a bob suspended from the end of a thread which is usually considered massless for easy and simplified calculation, if not stated otherwise.
The time period of a pendulum can be made longer by increasing the length of the thread it is suspended from, as measured from point of suspension to middle of the bob. If however we change the mass of the bob, there is not much difference observed in the time period, only if the length of thread is not affected. One factor which can change the time period of the pendulum is Earth’s gravitational field as it is not uniform at all points, hence in some places the pendulum will swing faster and in some areas it will swing slower than normal, which will change the time period of the pendulum.
One type of motion we know in Physics is that of Simple Harmonic motion, which basically includes repetitive movement back and forth following an equilibrium or central position so that maximum displacement on one side of position is equal to the maximum displacement on the other side. The time interval for each vibration will be hence the same, and the force responsible for the motion will always be directed towards equilibrium position and will be directly proportional to the distance from the equilibrium position.
Movement of pendulum is said to be simple harmonic motion because the restoring force acts directly proportional to the displacement and is directed towards the equilibrium position.
Hence, movement of the Pendulum is simple harmonic motion.

Note:When we talk about simple harmonic motion, another motion by the name of oscillatory motion comes into mind. It can be defined as the to and fro movement of an object from its mean position. Simple harmonic motion is one such type of oscillatory motion, from which we discuss the motion of the pendulum.