## 20131103

### Online reading assignment: ideal fluid flow, elasticity

Physics 205A, fall semester 2013
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 ideal fluid flow and elasticity.

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.
"Stress, strain, Hooke's law and elastic modulus were particularly interesting. I was trying to figure out a while ago if a specific straightedge made of high-carbon tool steel would deflect more cantilevered under its own weight than a specific straightedge made of aluminum. I made some guesstimations after some web searching but I'm getting close to being able to make my own estimations."

"That not all fluid types are ideal. I thought they were all the same."

"An ideal fluid should undergo laminar flow, where the adjacent particles flow smoothly past each other, as opposed to turbulent flow, where particles swirl around in a chaotic manner. I like the fact that many fluids, like water can undergo both laminar and turbulent flow."

"That the side of a smaller volume tube makes up for the volume shortage by just increasing the speed of whatever is going through it. I never gave it much thought, so it is interesting to fill in the blanks for everyday examples for physics."

"Watching the car in the wind tunnel was interesting because of the streamlines."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"Bernoulli's equation was a bit confusing because there are a lot of variables."

"So when a hose is collapsing, the pressure in that section of hose is decreased. Is the same true in a rigid pipe? That is, when the pipe's diameter decreases, does the pressure in that section decrease as well, regardless of whether or not the pipe is rigid?"

Describe at least one property ideal fluids have that real fluids don't have.
"An ideal fluid is not compressible."

"Ideal fluids have no viscosity."

"The particles are able to smoothly slip past each other rather than bump into each other and cause turbulence."

"Ideal fluids are always incompressible, they undergo laminar flow, and they also have no viscosity."

What are the SI units for volume flow rate?
"m3/s."

"kg/s."

In Bernoulli's equation, what are the SI units for the ρ·g·y term, and for the (1/2)·ρ·v2 term?
"Joules."

"J/m3."

"Pa."

An ideal fluid flowing from left-to-right along an expanding cross-section tube would experience a decrease in:
 speed. ****************** [18] volume flow rate. ******** [8] (Both of the above choices.) ******** [8] (Unsure/guessing/lost/help!) *** [3]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Q: When do sheep most like to go swimming in the river? A: When the flow is lamb-inar."

"Can you super-explain this section please! Bernoulli's equation. Practice problems?" (Yes, yes, yes--there will be time set aside in class for these.)

"I may be stressed, but I remain free from strain (for now)."

"I don't ever feel prepared for this class, no matter how much I read or do problems." (But you've tried, so you at least know what you don't know, and are letting me know what you need to know from class.)

"This flipped classroom method is still exacerbating my ability to learn in this class."

"What did you dress up as for Halloween?" (Nothing special. I just wore this t-shirt.)

"Will you be using the flipped classroom style in Physics 205B next semester?" (Imma try.)