SIMPLE HARMONIC MOTION

Repeated Motion

What are some examples of something that repeats?

What is common to all repeated things? Time interval Path taken How often

Special Repeated Motion

Called Simple Harmonic Motion (SHM) Two main requirements:

Repeated motion A force that constantly returns it to

equilibrium Examples of non-SHM:

Going to school Planets orbiting sun

Examples of SHM

Two main ones: Pendulum

An object swinging back and forth under the force of gravity

Spring System An object vibrating on a spring.

We will talk in this class only about pendulums.

Pendulums

Two important properties about SHM that we classify: Period (T)

The TIME it takes to make one complete repetition Measured in units of time (seconds, minutes, etc)

Frequency (f) The NUMBER of repetitions in one second

Measured in units of Hertz. (1/seconds)

Period and frequency are inversely related period = 1 / frequency

Pendulum Properties

What things DO affect the period of a pendulum? (brainstorm at table) Length Gravity

What things DO NOT affect the period of a pendulum? (brainstorm at table) Mass! Amplitude (how high you start it)

SHM Gives Sine Curves

If something moves in SHM, the graph of its motion is a sine curve.

We can see all the wave properties present in the sine curve.