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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!
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!
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!
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: 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
• 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!)