## 20121030

### Online reading assignment: static fluids

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 a presentation on static fluids.

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.
"Water pressure is pretty cool--more related to the calculus stuff I already know. Also as an architect-poser, I think hydrostatic pressure is important. Buoyancy is important too, but I won't be building boats I think."

"How a sphygmomanometer is able to measure blood pressure. To actually stop the blood flow with the pressure from the cuff and then release the pressure to hear the blood start to flow again....very interesting. I work in a physical therapy clinic and often times have to measure a patient's blood pressure."

"In the presentation preview that it shows the 'Man from Atlantis' withstanding pressure 20,000 feet underwater--that's a lot of pressure! Physics doesn't apply to such a man as that."

"Buoyancy is an interesting topic. I grew up around boats but never really understood the science behind them, and I would like to know more."

"Pressure does not have a direction it is scalar. This is interesting because I thought pressure was like force."

"Viewing living on Earth as on the bottom of an ocean of fluid called air."

"How the highest city in terms of elevation in the U.S. had an air pressure 30% lower than ours."

"Before taking blood from a donor, a drop of the blood is placed in a solution of known density. If the drop does not sink it is not safe for the person to give blood because the concentration of iron from red blood cells is too low."

"Density is really interesting, just because it's density."
Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"Formulas, dude. And how the shape of something in a fluid effects bouyancy."

"Why is pressure in pascals, and not mmHg or atm?" (They're all units of pressure, but pascals (or N/m2) is the preferred SI unit.)

"If the Greek letter ρ (rho) refers to the density of a submerged object, or the density of the fluid the object is in."

"I don't quite understand the pressure and why the air gets thinner at higher altitudes. I would like to hear more on this topic."

"Honestly, most things."

"These chapters weren't all that confusing."

"Buoyancy is confusing to me because I don't really understand what is being measured. I would benefit from some in-class discussion and/or examples."

"The difference in gauge pressure and absolute pressure."
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"I have a really hard time reading the orange pen on the whiteboard." (Agreed--I'll switch to another whiteboard marker color, even though it's Halloween.)

"What was the coolest Halloween costume you ever had?" (When Mrs. P-dog and I won a first-place Madonna Inn bakery cake for the Madonnaween costume contest a few years ago.)

"I'm not sure what to ask today."