Cuesta College, San Luis Obispo, CA
Students have a weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.
The following questions were asked on reading textbook chapters and previewing a presentation on sound.
Selected/edited responses are given below.
Describe something you found interesting from the assigned textbook reading or presentation preview, and explain why this was personally interesting for you.
"The speed of sound in air depends on the absolute temperature and that sound travels faster through warmer air and slower through cooler air."
"When dealing with an asymmetrical pipe, standing waves are produced only at odd multiples of the fundamental frequency."
"The subwoofer shredding the phonebook!"
"The different species of animals have different ways of communicating with each other with low frequency sound waves or high frequency sound waves."
"I love finding out how musical instruments and other various everyday things work."
"The human ear is only responsive to sound waves in a limited range of frequencies. Most humans cannot hear sounds within the full range. Other organisms would not survive if they could only hear the range of frequencies we are able to hear."
Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"I'm confused about the pipe section. I don't really understand the effects of an open versus closed-ends on pipes."
"Resonant frequencies, due to the different types and when they are valid."
"Nothing."
"I found it confusing to detect a sound wave because even transverse waves that make a sound do not qualify as a sound wave."
For sound waves, what does the T for sound wave speeds stand for, and what SI units does it have?
"The T stands for the temperature which is in kelvins (K)."
"The 'T' stands for period and the SI units are Hz or s-1."
FFor sound waves in air, classify each of these parameters are being "independent" (able to be changed without affecting other independent parameters), or "dependent" (will be changed when independent values are changed).
(Only correct responses shown.)
Amplitude A: independent [77%]
Wave velocity v : independent [67%]
Frequency f : independent [80%]
Wavelength λ : dependent [82%]
For sound waves in a tube, classify each of these parameters are being "independent" (able to be changed without affecting other independent parameters), or "dependent" (will be changed when independent values are changed).
(Only correct responses shown.)
Sound wave velocity v: independent [58%]
Tube length L: independent [66%]
Fundamental frequency f1: dependent [56%]
Frequency f of sound "blown" into tube: independent [69%]
Select the standing sound waves that would resonate in the tubes below.
(Only correct responses shown.)
Tube open at both ends: all multiples of f1 [42%]
Tube open at one end, and closed at the other end: only odd multiples of f1 [75%]
Tube closed at both ends: all multiples of f1 [62%]
What musical instrument(s) do you play? List none, or as many as applicable.
"None." [19 responses]
"Guitar." [9 responses]
"Piano." [14 responses]
"Air guitar."
"Singing." [5 responses]
"Flute." [4 responses]
"Does a triangle count?"
"Saxophone." [2 responses]
"Clarinet." [4 responses]
"Harmonica." [2 responses]
"Ukulele."
"Piccolo"
"Mandolin."
"Trumpet." [4 responses]
"Trombone." [2 responses]
"Drums." [2 responses]
"Cajón [Peruvian percussion box]."
"Banjo."
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"For wave propagation, we were saying that λ = v/f, where wavelength is the only one dependent in that relationship. Does the standing sound waves equation mean that frequency is dependent on wavelength, or does it only apply to the math?" (The fundamental frequency for sound waves in a tube is dependent on the length of the tube, and the speed of sound waves in air. However, the frequency of sound waves that go into the tube can be set independently, but will only produce resonance in the tube if it matches the fundamental frequency. Learning to play a woodwind or brass instrument is a trial-and-error process of varying your sound wave frequency (produced by a reed and/or your lips) to match the instrument's fundamental frequency.)
"For the upcoming midterm can you put additional problems from the textbook to practice in addition to the ones you give us in class?" (Well, most of the midterm study questions are similar questions from previous semesters' midterms.)
"What musical instrument(s) do you play?" (Piano, ukulele, and in grade school, the most played instrument in 20th century.)
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