What Is the Purpose of the Pendulum?

Pendulums are typically used for different scientific purposes.
••• Photos.com/Photos.com/Getty Images

A pendulum, derived from the Latin word "pendulus," meaning "hanging," is a body that hangs from a fixed point which, when pulled back and released, swings back and forth. It is the first direct visual evidence that demonstrates the rotation of the earth that isn't based on observing the stars circle in the sky. Almost every major science museum has a pendulum that you can see in motion.


The Italian physicist and astronomer Galileo Galilei discovered the principle of the oscillatory motion of the pendulum. He discovered the pendulum in 1581. In his experiments, Galilei established that the time it takes for the back-and-forth motion of a pendulum of a given length remains the same even if its arc, or amplitude, decreases. Through the pendulum, Galilei discovered isochronisms, the pendulum's most important characteristics, which make them useful in measuring time.

Pendulum's Forces

Pendulums act upon different forces.The pendulum's inertia -- the resistance of a physical object -- is what makes the pendulum swing straight out and up. The downward force of gravity, which is the force that causes two objects to pull toward each other, is what pulls the pendulum straight back. Another force, air resistance, which determines the pendulum's velocity, makes a pendulum swing in shorter arcs.

How Pendulums Work

A so-called simple pendulum consists of a mass, or weight known as a bob, hanging from a string, or cable, of a certain length and fixed at a pivot point. When shifted from its starting position to an initial angle and released, the pendulum swings back and forth freely with periodic motion. All simple pendulums should have the same period, which is the time for one complete cycle of a left swing and a right swing, regardless of their initial angle.


Different kinds of pendulums include the bifilar pendulum, the Foucault pendulum and the torsion pendulum. A bifilar pendulum has been used to record the irregular rotation of the earth as well as to detect earthquakes. The Foucault pendulum, which French physicist Leon Foucault invented, is used to demonstrate the rotation of the earth. A torsion pendulum, although not strictly a pendulum because it doesn't oscillate because of the force of gravity, is often used for time-keeping purposes, such as regulating the movement of clocks.

Related Articles

How to Calculate the Period of Pendulum
Why Is a Pendulum Scientifically Important?
Different Types of Pendulums
What Affects the Swing Rate of a Pendulum?
How to Calculate the Period of Pendulum
Why Does a Pendulum Swing?
What Can Cause a Change in Velocity?
History of the Pendulum
Objects Which Use Pendulum Movement
What Is the Shape of Earth's Orbit?
List of Discoveries of Galileo Galilei
The Factors That Might Affect the Period of Oscillation
What Astronomical Instrument Measures the Brightness...
What is Inertia?
The Use of Pendulums in the Real World
How to Calculate Centrifugal Force
What Are the Uses of Pendulums?
What Are the Parts of a Pendulum?
What Are the Two Motions of the Earth?

Dont Go!

We Have More Great Sciencing Articles!