May 20 & 21B day & A Day

Ch 26 Day 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**

Can ‘frequency’ be measured?

1. 2. 3.

100%

0%0%

1. Yes2. No3. Not sure

Can ‘pitch’ be measured?

1. 2. 3.

26%

0%

74%1. Yes2. No3. Not sure

What is the average frequency range of a young person’s

hearing?

1. 2. 3. 4. 5.

0%

9%

0%

87%

4%

1. 20 Hz to 20 kHz2. 10 Hz to 20 Hz3. 20 Hz to 200 Hz4. 20 Hz to 20,000 kHz5. Not sure

CAREFUL!!!1 kHz = 1000 Hz

Older humans typically have a ____ hearing range than younger people,

especially on the ___ frequency side.

1. 2. 3. 4. 5.

0%4%

0%

12%

84%1. bigger, high2. bigger, low3. smaller, high4. smaller, low 5. Not sure

Be nice to your grandparents!

Sound travels in a ______wave.

1. 2. 3. 4.

38%

0%

10%

52%1. Transverse2. Longitudinal 3. Either 1 or 24. Neither 1 nor 2

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.

Infrasonic sounds are ____ than ___ Hz.

1. 2. 3. 4. 5. 6. 7.

0%

10%

14%

0%

14%

57%

5%

1. More, 102. More, 203. More, 20,0004. Less, 105. Less, 206. Less, 20,0007. Not sure

Ultrasonic sounds are ____ than ___ Hz.

1. 2. 3. 4. 5. 6. 7.

5%

33%

62%

0%0%0%0%

1. More, 102. More, 203. More, 20,0004. Less, 105. Less, 206. Less, 20,0007. Not sure

Light CAN travel through a vacuum (evidence – we see sun, moon, stars,

etc…)… but can SOUND travel through a vacuum?

1. 2. 3.

10%0%

90%1. Yes2. No 3. Not sure

Science fiction = WRONG! FICTION!

*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?

1. 2. 3.

15%

0%

85%

1. Putty2. Steel 3. Not sure

Does sound travel better/faster in elastic or inelastic solids?

1. 2. 3.

88%

0%

13%

1. Elastic2. Inelastic 3. Not sure

The speed of sound in dry, ROOM TEMPERATURE air is about…

1. 2. 3. 4. 5. 6.

17%

74%

0%0%4%4%

1. Approx. 330 m/s2. Approx. 340 m/s 3. Approx. 198m/s 4. Approx. 6600 m/s 5. Approx. 12 m/s 6. Correct answer is not

listed

Sound travels fastest to slowest in the following order:

1. 2. 3. 4. 5. 6. 7.

48%

4%

40%

0%

4%

0%

4%

1. Solids, liquids, gasses2. Solids, gasses, liquids3. Gasses, liquids, solids4. Gasses, solids, liquids5. Liquids, solids, gasses6. Liquids, gasses, solids7. Not sure

Sounds travels _____ in a hotter medium, than the identical

medium that is colder

1. 2. 3. 4.

65%

0%0%

35%

1. Faster2. Slower3. The same4. Not sure

Hotter = more energy = easier for sound to

‘bounce’ thru the medium!

Sounds travels _____ humid air, than dry air of identical

temperature

1. 2. 3. 4.

24%

0%

24%

52%1. Faster2. Slower3. The same4. Not sure

Humid = closer to liquid!

True or False: The 2 pennies in the dropped penny demo are made from identical materials.

1. 2. 3.

13%

0%

87%1. True2. False 3. Not sure

Natural frequency = like a fingerprint…Diff. materials have dif. N.F.

The tuning fork on table demo is an example of….

1. 2. 3. 4.

13%

0%0%

88%1. Resonance2. Forced vibration3. Beats 4. Not sure

Like acoustic guitars

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

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!

True or false: INTENSITY of a sound can be measured.

1. 2. 3.

0% 0%0%

1. True 2. False 3. Not sure

True or false: LOUDNESS of a sound can be measured.

1. 2. 3.

0% 0%0%

1. True 2. False 3. Not sure

It is our SUBJECTIVE

interpretation of intensity

The intensity of a sound is__________ proportional to the amplitude squared of the sound wave

1. 2. 3.

0% 0%0%

1. Directly2. Inversely 3. Not sure

True or False: Sound cannot cancel sound.

1. 2. 3.

0% 0%0%

1. True2. False 3. Not sure

BOSE/ Beats headphones, white noise machines,

construction headphonesDESTRUCTIVE interference

Both waves have the same speed in the same medium. Use a ruler to answer the following…

Which wave has the greater amplitude?

1. 2. 3. 4.

0% 0%0%0%

1. A2. B3. Same4. Not sure

Both waves have the same speed in the same medium. Use a ruler to answer the following…

Which wave has the greater wavelength?

1. 2. 3. 4.

0% 0%0%0%

1. A2. B3. Same4. Not sure

Both waves have the same speed in the same medium. Use a ruler to answer the following…

Which wave has the greater frequency?

1. 2. 3. 4.

0% 0%0%0%

1. A2. B3. Same4. Not sure

Both waves have the same speed in the same medium. Use a ruler to answer the following…

Which wave has the greater period?

1. 2. 3. 4.

0% 0%0%0%

1. A2. B3. Same4. Not sure

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?

1. 2. 3. 4.

0% 0%0%0%

1. A2. B3. Same4. Not sure

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?

1. 2. 3. 4.

0% 0%0%0%

1. A2. B3. Same4. Not sure

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?

1. 2. 3. 4.

0% 0%0%0%

1. A2. B3. Same4. Not sure

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

• 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.

26.10 Beats – not on test

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).

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!)