## 20121118

Physics 205A, fall semester 2012
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 presentations 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.
"That sound is caused by air compressions and rarefactions."

"This section is my favorite so far. I can see the concept of sound waves and frequency, etc., more so than anything else we've studied. Maybe that's why I play music."

The different frequencies of sound that animals can distinguish was very interesting knowing what a human's range is only within 20 Hz to 20 kHz."

"My favorite part of physics, sound waves. I play a few instruments and sound waves have always been interesting to me."

"Crazy how a subwoofer can shred a phonebook; I was surprised that it wasn't hurting the man at all either."

"That temperature makes a difference in the speed of the sound waves. and while i think that is super interesting I don't really get why it makes a difference. I guess the molecules are hitting each other more often but it is still a little confusing."

"Being a trombone player, I really didn't see the physics behind playing different intervals on one slide position, so that video shed a new light on playing the trombone."
Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"Even though humans can't hear below 20 Hz, can we feel the rumble? It seems like we would be able to."

"What is a standing sound wave? I have no idea what is going on there."

"Why again does temperature affect sound wave speed?"
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Do you play any instruments?" (Piano and ukulele (but not very seriously), but in grammar school I did manage to play the most-played instrument of my generation...)

"I don't like waves. Can we please go back to projectile motion please?"

"As far as the frequencies that some animals can hear but we cannot, why are we not able to hear them? Are the higher frequencies really high-pitched?" (The physiology of our ears are not responsive enough to those very high frequencies--and even the sensitivity of frequencies within the high end of human hearing degrades with age. Are you still young enough to hear the Mosquito (or Teen Buzz) ringtone?)