2. & Simple Harmonic Motion

3. Any periodically repeating event. (Ex: waves, pendulums, heartbeats, etc.) http://www.exploratorium.edu/xref/phenomena/simple_harmonic_motion.html

4. Waves A disturbance in space and time which repeats itself regularly and transfers energy without actually transporting the matter it propagates through.

5. All waves have: Wavelength- ( ) distance from crest to crest Frequency- (f) # waves past a given point per second (s -1 ) Amplitude- height of wave from crest to origin

6. Two Types of Waves Transverse: –particle motion is ┴ to the motion of energy transfer. http://www.kettering.edu/~drussell/Demos/waves/wavemotion.html wavelength (λ) amplitude nodes antinodes

7. EMS

8. Two Types of Waves (cont’d) Longitudinal: particle motion is ║ to the motion of energy transfer. –‘compressions’ and ‘rarefactions’ –like sound waves

9. Measuring Periodic Motion Frequency (f): –cycles per second –UNIT: hertz (Hz) Period (T): –seconds per cycle –UNIT: seconds (s) Back and forth… f = 1 / T T = 1 / f

10. Wave Speed v = λ f If no v is given, use the speed of light (c) for speed (v = 3.0 x10 8 m/s) velocity (m/s) wavelength (m) frequency (Hz)

11. Try These… Ocean waves are 8m long and one passes by you every 4 seconds. 1.What is the wave’s period? 2.What is the wave’s frequency? 3.What is the speed of the wave?

12. Sound Sound travels through space as a longitudinal wave, transmitted by vibrations of air molecules. –It is important to realize that energy is being transported and not the air particles themselves.

13. Compressions & Rarefactions Remember: sound waves move in 3-D

14. Doppler Effect The apparent change of frequency due to the motion of the observer (or source). http://www.lon-capa.org/~mmp/applist/doppler/d.htm http://paws.kettering.edu/~drussell/Demos/doppler/doppler.html

15. Beats When two similar sound waves interfere with one another, they create beat patterns. These beat patterns are easily determined by subtracting the frequencies. http://www.upscale.utoronto.ca/PVB/Harrison/Flash/ClassMechanics/Beats/Beats.swf Practice: A 400Hz tuning fork is struck, which other frequencies will create beats of 1Hz 3Hz

16. Intensity Intensity is the variance of waves by change of amplitude (volume in sound). Notice that these two waves have the same frequency, but different intensities.

17. Pitch Pitch is the variance of waves by change of frequency. Notice that these two waves have the same volume, but different frequencies.

18. Resonance Every object has a natural frequency at which it begins to vibrate. If it happens to be exposed to sound waves at this frequency, it will instantly begin to vibrate. This is resonance. http://www.youtube.com/watch?v=3mclp9QmCGs

19. Diffraction Diffraction is defined as the spreading out of a wave as it goes around a corner. This property applies, in some sense, to all waves.

20. Some Questions... 1. Is sound able to travel in a vacuum? Why or why not? 2.Does changing the intensity of a sound change the frequency of the sound itself? 3.If a sound source is moving away from you, you hear the frequency as LOWER/HIGHER than it actually is. 4.(T/F) The Doppler Effect only applies to moving sources and not moving observers.