May 20 & 21 B day & A Day

1. May 20 & 21B day & A Day Ch 26 Day 2

2. Do Now • Take a clicker • Turn in HW • Take out CH 26 POGIL #1 and get ready for a rapid review Tonight’s HW • TEST next class!!! **Test May 23 A day & May 27 B day on CH 25 & 26**

3. Can ‘frequency’ be measured? • Yes • No • Not sure

4. Can ‘pitch’ be measured? • Yes • No • Not sure

5. What is the average frequency range of a young person’s hearing? • 20 Hz to 20 kHz • 10 Hz to 20 Hz • 20 Hz to 200 Hz • 20 Hz to 20,000 kHz • Not sure CAREFUL!!! 1 kHz = 1000 Hz

6. Older humans typically have a ____ hearing range than younger people, especially on the ___ frequency side. • bigger, high • bigger, low • smaller, high • smaller, low • Not sure Be nice to your grandparents!

7. Sound travels in a ______wave. • Transverse • Longitudinal • Either 1 or 2 • Neither 1 nor 2

8. Important DISCLAIMER: Many of the diagrams represent a sound wave by a sine wave, which resembles a transverse wave and may mislead people into thinking that sound is a transverse wave. Sound is not a transverse wave, but rather a longitudinal wave. Nonetheless, the variations in pressure with time take on the pattern of a sine wave and thus a sine wave is often used to represent the pressure-time features of a sound wave. In English: Machines that measure LOUDNESS have a screen that displays a sine wave to model the readings.

9. Infrasonic sounds are ____ than ___ Hz. • More, 10 • More, 20 • More, 20,000 • Less, 10 • Less, 20 • Less, 20,000 • Not sure

10. Ultrasonic sounds are ____ than ___ Hz. • More, 10 • More, 20 • More, 20,000 • Less, 10 • Less, 20 • Less, 20,000 • Not sure

11. Light CAN travel through a vacuum (evidence – we see sun, moon, stars, etc…)… but can SOUND travel through a vacuum? • Yes • No • Not sure Science fiction = WRONG! FICTION!

12. *You are about to read a ‘Bones’ definition. Not from the book, but it might make a little more sense* Remember – ELASTIC means an object can be thrown against a wall and not be smashed/ disfigured!What is MORE ELASTIC, putty or steel? • Putty • Steel • Not sure

13. Does sound travel better/faster in elastic or inelastic solids? • Elastic • Inelastic • Not sure

14. The speed of sound in dry, ROOM TEMPERATURE air is about… • Approx. 330 m/s • Approx. 340 m/s • Approx. 198m/s • Approx. 6600 m/s • Approx. 12 m/s • Correct answer is not listed

15. Sound travels fastest to slowest in the following order: • Solids, liquids, gasses • Solids, gasses, liquids • Gasses, liquids, solids • Gasses, solids, liquids • Liquids, solids, gasses • Liquids, gasses, solids • Not sure

16. Sounds travels _____ in a hotter medium, than the identical medium that is colder • Faster • Slower • The same • Not sure Hotter = more energy = easier for sound to ‘bounce’ thru the medium!

17. Sounds travels _____ humid air, than dry air of identical temperature • Faster • Slower • The same • Not sure Humid = closer to liquid!

18. True or False: The 2 pennies in the dropped penny demo are made from identical materials. • True • False • Not sure Natural frequency = like a fingerprint… Diff. materials have dif. N.F.

19. The tuning fork on table demo is an example of…. • Resonance • Forced vibration • Beats • Not sure Like acoustic guitars

20. Today’s Tasks • B day – we are going to CONTINUE the CH 26 POGIL #2 • Resonance YouTube Video • Constructive vs Destructive Interference • Loudness vs Intensity • Articles

21. Today’s Tasks Finish this POGIL by 10:15 then we are stopping for an exit! Check in at stop signs….either with teacher or in text. YOUR responsibility to do so!

22. True or false: INTENSITY of a sound can be measured. • True • False • Not sure

23. True or false: LOUDNESS of a sound can be measured. • True • False • Not sure It is our SUBJECTIVE interpretation of intensity

24. The intensity of a sound is__________ proportional to the amplitude squared of the sound wave • Directly • Inversely • Not sure

25. True or False: Sound cannot cancel sound. • True • False • Not sure BOSE/ Beats headphones, white noise machines, construction headphones DESTRUCTIVE interference

26. Both waves have the same speed in the same medium. Use a ruler to answer the following…Which wave has the greater amplitude? • A • B • Same • Not sure

27. Both waves have the same speed in the same medium. Use a ruler to answer the following…Which wave has the greater wavelength? • A • B • Same • Not sure

28. Both waves have the same speed in the same medium. Use a ruler to answer the following…Which wave has the greater frequency? • A • B • Same • Not sure

29. Both waves have the same speed in the same medium. Use a ruler to answer the following…Which wave has the greater period? • A • B • Same • Not sure

30. Shown to the right are 2 different pairs of transverse wave pulses that move toward each other. At some point in time the pulses meet and interact (interfere) with each other.Which results in a larger AMPLITUDE when they meet? • A • B • Same • Not sure

31. Shown to the right are 2 different pairs of transverse wave pulses that move toward each other. At some point in time the pulses meet and interact (interfere) with each other.Which results in CONSTRUCTIVE interference? • A • B • Same • Not sure

32. Shown to the right are 2 different pairs of transverse wave pulses that move toward each other. At some point in time the pulses meet and interact (interfere) with each other.Which results in DESTRUCTIVE interference? • A • B • Same • Not sure

33. Don’t Forget… • Bring your notes with you to class on Tuesday • There MIGHT be extra credit for bringing them! • You have a TEST on Tuesday! • Meme Project - - - Due June 7th • Groups of 1-4 • 46 points • Anything you learned all year • DO NOT: • Turn in one that you’ve already done • Copy off the internet

34. 26.10 Beats – not on test • Ever been next to a LOUD fan/engine, and hummed? • Beats are rapid changes in the loudness/ intensity of a sound when two tones very close in frequency are heard together. • They interfere with one another! • The diagram illustrates the wave interference pattern resulting from two waves (drawn in red and blue) with very similar frequencies.

35. A beat pattern happens when WAVE amplitude changes at a regular rate. The beat pattern (drawn in green) repeatedly oscillates from zero amplitude to a large amplitude Points of constructive interference (C.I.) and destructive interference (D.I.) are labeled on the diagram. When constructive interference occurs between two crests or two troughs, a loud sound is heard. This corresponds to a peak on the beat pattern (drawn in green).

36. When destructive interference (DI) between a crest and a trough occurs, no sound is heard • Amplitude relates to volume… so this beat pattern would be consistent with a wave which varies in volume at a regular rate. • A piano tuner utilizes beats to tune a piano string. • She will pluck the string and tap a tuning fork at the same time. If the two sound sources - the piano string and the tuning fork - produce detectable beats then their frequencies are not identical. • She will then adjust the tension of the piano string and repeat the process until the beats can no longer be heard. • As the piano string becomes more in tune with the tuning fork, the beat frequency will be reduced and approach 0 Hz. • SUPPOSE in this process, the piano is tuned at 496 Hz and the fork is 494 Hz. What will be the beat frequency? • 496-494 = 2 Hz • No beats = same frequency! (496-496 = 0!)