May 20 & 21B day & A Day

Ch 26 Day 2

Tonight’s HW

• Read & Study 25.9-25.11, • do #15-20 p. 388• Read & Study: 26.8-26.9• do #13-18 p. 402• 13 points - 1 per question, and 1 for

correctness**Test May 23 A day & May 27 B day on CH 25 & 26**

B DAY: Get a Clicker and Take an Do Now HINT – you may need to reference #17 in your Ch 26 POGIL #1 to solve

1. A bat flying in a room temperature cave emits a sound pulse and receives its echo in 1 second. How far away is the cave wall?

2. A sound travels in room temperature air. It takes 0.03 seconds for one sound wave to occur.

a. What is the wavelength of the sound wave? b. Can a human hear this sound wave?c. Can a dog hear this sound wave?

A bat flying in a room temperature cave emits a sound pulse and receives its echo in 1 second. How far away is the cave wall?

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

63%

13% 13%

0%

13%

0%

1. Less than 170 m2. 170-171 m3. Between 171 - 340 m4. 340-342 m5. More than 342 m6. Not enough info to solve.

1. A bat flying in a room temperature cave emits a sound pulse and receives its echo in 1 second. How far away is the cave wall?

• What do we know?• Room temperature air = sound wavespeed of 342 m/s

(or 340 if you rounded)• Wavespeed = distance traveled / time

• 342 m/s = x / 1s

• 342 m/s = 342m / 1s• Which means that since it was an ECHO, the cave wall is

171 m away! – (travels 171 m there, and 171 m back, for a total distance of

342 m)

Regarding #1, how do you feel?

1. 2. 3. 4.

8% 8%

25%

58%

1. I have no clue what is going on

2. I think I’ll be ok with more practice

3. I did not get this correct the first time, but I know how to fix my error in the future

4. I got this correct the first time and I know what I am doing sow ell I could teach it to others!

2. A sound travels in room temperature air. It takes 0.03 seconds for one sound wave to occur. A. What is the wavelength of the sound wave? B. Can a human hear this sound wave?C. Can a dog hear this sound wave?

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

44%

11%

0%

33%

11%

0%

1. Approx. 10.2 m2. Approx. 33.3 m3. Approx. 342 m4. Approx. 11,322 m5. Correct answer is not

listed6. Not enough info to solve.

2. A sound travels in room temperature air. It takes 0.03 seconds for one sound wave to occur.

a. What is the wavelength of the sound wave? b. Can a human hear this sound wave?c. Can a dog hear this sound wave?

What do we know?• Room temperature air = sound wavespeed of 340

or 342 m/s• 0.03 seconds for one sound wave is the period• Frequency = 1/ period• f = 1/ (0.03) f = 33.3 Hz (in other words, there

are 33 waves per second)

1. A sound travels in room temperature air. It takes 0.03 seconds for one sound wave to occur.

a. What is the wavelength of the sound wave? b. Can a human hear this sound wave?c. Can a dog hear this sound wave?

340= 33.3

= 10.2 m

#2 – can a human hear this sound?

1. 2. 3.

9%0%

91%

1. Yes2. No 3. Not enough info to solve

33.3 Hz = withinHuman hearingRange

#2 – can a dog hear this sound?

1. 2. 3.

36%

0%

64%

1. Yes2. No 3. Not sure

33.3 Hz = NOT withindog hearingRange

Regarding #2, how do you feel?

1. 2. 3. 4.

17%

0%

25%

58%

1. I have no clue what is going on

2. I think I’ll be ok with more practice

3. I did not get this correct the first time, but I know how to fix my error in the future

4. I got this correct the first time and I know what I am doing sow ell I could teach it to others!

A DAY: Take a Meme Rubric and have a seat!

Today’s Tasks • B day – we are going to begin the CH 26 POGIL #2– Doppler Ball Demo– Shock Waves vs Bow Waves– Hearing Test via Mosquito Ring tone

• A day – we are going to finish the CH 26 POGIL #2– Doppler Ball Demo– Shock Waves vs Bow Waves– Hearing Test via Mosquito Ring tone – Resonance YouTube Video– From now until 10 minutes before the bell to finish the

POGIL!

Can ‘frequency’ be measured?

1. 2. 3.

0% 0%0%

1. Yes2. No3. Not sure

Can ‘pitch’ be measured?

1. 2. 3.

0% 0%0%

1. Yes2. No3. Not sure

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

hearing?

1. 2. 3. 4. 5.

0% 0% 0%0%0%

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% 0% 0%0%0%

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.

0% 0%0%

1. Transverse2. Longitudinal 3. Not sure

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% 0% 0% 0%0%0%0%

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.

0% 0% 0% 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.

0% 0%0%

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.

0% 0%0%

1. Putty2. Steel 3. Not sure

Does sound travel better in elastic or inelastic solids?

1. 2. 3.

0% 0%0%

1. Elastic2. Inelastic 3. Not sure

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

1. 2. 3.

0% 0%0%

1. 330 m/s2. 340 m/s (or 342 m/s

if you don’t round)3. Not sure

Sound travels fastest to slowest in the following order:

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

0% 0% 0% 0%0%0%0%

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.

0% 0%0%0%

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.

0% 0%0%0%

1. Faster2. Slower3. The same4. Not sure

Humid = closer to liquid!

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 headphones

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

1. 2. 3.

0% 0%0%

1. True2. False 3. Not sure

Natural frequency

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

1. 2. 3. 4.

0% 0%0%0%

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

Like acoustic guitars

Constructive Interference

• When is it a good thing?• When is it a bad thing?

Destructive Interference

• When is it a good thing?• When is it a bad thing?

• In a transverse wave, the direction in which the wave energy travels is Perpendicular to the wave pulse.– THINK: T for transverse is the symbol for

perpendicular • In a longitudinal wave, the direction in which

the wave energy travels is Parallel to the wave pulse.– THINK: longitudinal starts and ends with ‘l’…ll is the symbol for perpendicular!

• Everyone gets +2 on Genesis for #13-14 on quiz

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

• 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!)