Definition:Pendulum/Simple

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Definition

A simple pendulum is an ideal body consisting of two parts:

$(1): \quad$ a rod attached at one end to a pivot
$(2): \quad$ a point mass at the other end of the rod

embedded in a gravitational field.


Pendulum.png


Bob

The point mass at the free end of the rod of a simple pendulum is called the (pendulum) bob.

Hence the bob is free to swing under the effects of the gravitational field.


Period

The period of a simple pendulum is the time period through which the bob takes to travel from one end of its path to the other, and back again.


Ideals

The ideals of a simple pendulum are as follows:

The rod is of zero thickness, infinite stiffness and zero mass.
The pivot is immovable and has zero friction.
The bob is of zero volume.
The gravitation field is (usually) taken to be constant and uniform.
The medium in which the simple pendulum moves offers no resistive force, unless otherwise specifically stated.


Also defined as

In their definitions of a simple pendulum, some treatments specify that, instead of a rod, the bob is suspended from the pivot by a cord.

The treatment is similar to that of the rod, but the behaviour of the simple pendulum when the bob rises above the pivot is different.

In all cases, the statement of the problem should define which arrangement is in effect.


Also known as

A simple pendulum as defined on $\mathsf{Pr} \infty \mathsf{fWiki}$ is often referred to as just a pendulum.


Also see

  • Results about simple pendulums can be found here.


Linguistic Note

The word pendulum is a neo-Latin word, deriving from the Latin pendulus, meaning hanging.


Sources