1. Harmonic Motion
Motion in Cycles

2. What is Harmonic Motion?
Motion that repeats; occurs in cycles.
Cycle:
Unit of motion that repeats over and over.
Examples:
Pendulums, Earth’s movements, sound or light waves.

3. Oscillation Oscillation: Oscillator: Vibration:
Motion that repeats regularly.
Oscillator:
A system with harmonic motion
Example: Solar system, heart and surrounding muscles
Vibration:
Motion that varies back and forth; fast movement

4. Describing Harmonic Motion
Period:
Time for one cycle to occur.
Units: seconds (sec)
Frequency:
Number of cycles per second.
Units:
1/sec or Hertz (Hz)
Amplitude:
Describes the size of a cycle; Units = meters (m)

6. Examples of Period/Frequency Problems
The period of an oscillator is 15 minutes. What is the frequency of this oscillator in hertz?
Remember 1 minute = 60 sec

7. Examples of Period/Frequency Problems
2. The period of an oscillator is 2 minutes. What is the frequency of the oscillator in Hertz?

8. Examples of Period/Frequency Problems
How often would you push someone on a swing to create a frequency of 0.20 Hertz?

9. Graphing Harmonic Motion
Let’s Make some Graphs!

10. Linear Graphs vs. Harmonic Graphs

12. Determining the period and amplitude from a Graph
Start by identifying one wave cycle (peak to peak)
Period = ending time – starting time
Amplitude = ½ (high point – low point)
Let’s go back and calculate the period and amplitude of the harmonic graph on the last slide!