1. Ch 12

2. Lab #70 Pg 261 Objective: – To observe important wave properties Warm-Up (12.3) – Define fundamental frequency – What happens to frequency as harmonic number increases?

3. Exit Ticket None

4. 12.1 Objective: – Production and Characteristics of sounds waves – Doppler Effect Warm-Up (12.1) – How does density and pressure relate to compression and rarefaction?

5. Soundwaves are longitudinal (parallel to direction of movement)

8. We can hear 20-20,000Hz Dogs can hear ultrasonic high frequency http://www.bing.com/videos/search?q=dog+ultrasonic&view=detail&&&mid=6232F1FED971021916676232F1FED97102191667&rvsmid=6232F1FED97102191667 6232F1FED97102191667#view=detail&mid=6232F1FED971021916676232F1FED97102191667 http://www.bing.com/videos/search?q=dog+ultrasonic&view=detail&&&mid=6232F1FED971021916676232F1FED97102191667&rvsmid=6232F1FED97102191667 6232F1FED97102191667#view=detail&mid=6232F1FED971021916676232F1FED97102191667 Elephants can hear infrasonic low frequency http://www.bing.com/videos/search?q=elephant+infrasonic&view=detail&&&mid=9E9AB33252972F0BD28B9E9AB33252972F0BD28B&rvsmid=9E9 AB33252972F0BD28B9E9AB33252972F0BD28B#view=detail&mid=9E9AB33252972F0BD28B9E9AB33252972F0BD28B http://www.bing.com/videos/search?q=elephant+infrasonic&view=detail&&&mid=9E9AB33252972F0BD28B9E9AB33252972F0BD28B&rvsmid=9E9 AB33252972F0BD28B9E9AB33252972F0BD28B#view=detail&mid=9E9AB33252972F0BD28B9E9AB33252972F0BD28B Pitch- how high or low a sound is perceived to be Solids waves travel faster b/c particles are closer High temp particles move faster and waves travel faster

10. Doppler Effect Frequency shift as sound moves toward you and then away

11. Exit Ticket Pg 413 1-7

12. 12.2 Objective: – Sound intensity formula – Learn what the decibel levels – Learn about resonance Warm-Up – Get out HW

13. Intensity Piano wire vibrates and transfers energy to the piano’s sound board which transfers energy into the air as sound. – The rate at which this occurs is called intensity – EX: What is the intensity of the soundwaves produced by a trumpet at a distance of 3.2m when the power output of the trumpet is 0.20W?

14. Intensity/Frequency graph Pg 416 Decibel (dB)= intensity of soundwave/intensity of threshold of hearing Sound/softest No units

15. Forced vibrations and resonance Pluck a guitar string and the vibration is forced to the bridge (forced vibrations) which is forced to the body (sympathetic) which allows energy exchange between string and air which increases intensity Pendulum’s natural frequency depends on length. If each pendulum has same natural frequency then the frequency transfers= resonance – A bridge can do this, wind causes the bridge to vibrate and high winds cause bridge to oscillate at it’s natural frequency which increases until it breaks. http://www.bing.com/vide os/search?q=tuning+fork+r esonance&view=detail&mi d=008444A92CB7D6752AB 1008444A92CB7D6752AB1 &FORM=VIRE3 http://www.bing.com/vide os/search?q=troops+march ing+in+natural+frequency+ of+bridge&view=detail&& &mid=D8B80A1C110379BC 596AD8B80A1C110379BC5 96A&rvsmid=E89802D682B C6C89F3E6E89802D682BC 6C89F3E6&fsscr=0&ajf=70

16. Exit Ticket 415 1a, 3, 5 420 1, 2, 5

17. 12.3 Objective: – Harmonics in a string, open system and closed system Warm-Up (12.3) – How does lambda and Length relate…it’s a formula but not a highlighted one? – Now substitute lambda in the v=fx formula – Get out HW

18. Standing waves Open – End of a string wh. Cannot vibrate= node – Pipe is open at both ends it has antinodes at end Closed

20. Open

21. Example 1 One string on a toy guitar is 34.5 cm long. – What is the wavelength of its first harmonic – The string is plucked and the speed of the waves on the string is 410 m/s. What are the frequencies of the first three harmonics?

22. Example 2 What are the first three harmonics in a 2.45m long pipe that is open at both ends? Assume that the speed of sound in air is 345 m/s.

23. Closed

24. Example 3 What are the first three harmonics in a 2.45m long pipe that is closed at both ends? Assume that the speed of sound in air is 345 m/s.

25. Exit Ticket none

26. Lab Objective: – Calculate the speed of sound Warm-Up https://www.youtube.c om/watch?v=M8_PgO5 Hks0 https://www.youtube.c om/watch?v=M8_PgO5 Hks0

27. Exit Ticket http://lab.andre-michelle.com/playing-with- pulse-harmonics http://lab.andre-michelle.com/playing-with- pulse-harmonics

28. 12.3 Objective: – Harmonics in a string, open system and closed system Warm-Up: – If f= v/x and x=4L/3 then substitute x into the first equation and simplify the equation.

29. Go to green slides

30. Exit Ticket 427 1-4