1. Waves Types and Characteristics

2. What are some definitions of “medium?” When dealing with waves, a medium is the material through which a wave travels.

3. Mechanical Waves A mechanical wave occurs when a source of energy causes a vibration to travel through a medium. Important!!! The medium itself experiences no net movement! Think of “the wave” at a baseball game.

4. Example Stadium wave Stadium wave Stadium wave Stadium wave

5. Mechanical Wave Types - Transverse Movement of medium is perpendicular to direction of energy flow. Movement of medium is perpendicular to direction of energy flow. movementenergy

6. Mechanical Wave types - Longitudinal Movement of medium is parallel to direction of energy flow. movementenergy

7. Transverse Wave Parts crest trough

8. Longitudinal Waves Parts compression rarefaction

9. On the Back: Complete the Map!

10. Characteristics of Waves Wavelength (λ): the distance of one complete wave (crest to crest or trough to trough)

11. Characteristics of Waves Amplitude: the height of one wave Amplitude: the height of one wave (from resting point to crest or trough)

12. Characteristics of Waves Frequency (f): the number of full cycles (crest to crest) a wave goes through every second. Frequency (f): the number of full cycles (crest to crest) a wave goes through every second. f = # of cycles time UNITS: cycles/sec Hertz

13. Frequency A wave is being driven so that it goes through 5 cycles every 10 seconds. What is the frequency of the wave? A wave is being driven so that it goes through 5 cycles every 10 seconds. What is the frequency of the wave? The frequency of a wave is 60 Hz. How many cycles will it go through in 2.5 seconds? The frequency of a wave is 60 Hz. How many cycles will it go through in 2.5 seconds?

14. Characteristics of Waves Recall: velocity = D velocity = velocity = v = λf v = λf frequencywavelength xtt = D · 1

15. Wave Speed A wave has a frequency of 50 Hz and a wavelength of 3 meters. What is the wave speed? A wave has a frequency of 50 Hz and a wavelength of 3 meters. What is the wave speed? A wave has a speed of 2 m/s. If the wave has a frequency of 10 Hz, what is its wavelength? A wave has a speed of 2 m/s. If the wave has a frequency of 10 Hz, what is its wavelength?

16. http://www.youtube.com/watch?v=77slIdkkQWg Bill Nye Song

17. Extension - Some Demos Tacoma Narrows Tacoma Narrows Tacoma Narrows Tacoma Narrows Waves on a Rope Waves on a Rope Shattering Glass Shattering Glass Shattering Glass Shattering Glass

18. Exploration In your notes, describe what you see with the slinky. Draw a picture! In your notes, describe what you see with the slinky. Draw a picture! Is this a longitudinal or transverse wave? Is this a longitudinal or transverse wave? What do you notice about the position (or change of position) of each part of the slinky? What do you notice about the position (or change of position) of each part of the slinky? This is called a standing wave This is called a standing wave

19. Standing Waves A standing wave is a wave that has points that are always at rest. These are called “nodes.” Node

20. Standing Waves When we put energy into something at just the right frequency, it will resonate! Watch the footage again of the Tacoma narrows bridge and the shattering glass.

21. Images Cited www.bottomlayer.com www.bottomlayer.com www.bottomlayer.com www.howstuffworks.com www.howstuffworks.com www.howstuffworks.com