## 20141208

### Online reading assignment: heat transfer applications

Physics 205A, fall semester 2014
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 heat transfer applications.

Selected/edited responses are given below.

Describe what you understand from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically demonstrate your level of understanding.
"Thermodynamics can create potentially profitable consumer products."

"Cooper Cooler™ cools beverages by spinning them, we will test if spinning the can will cool the beverage faster. Coffee Joulies™ have a phase-changing material that will allow the liquid (most likely coffee) to be cooled down to drinking temperature and retain the heat longer."

"Each of these products are designed to either encourage or inhibit heat loss."

"A space blanket works as a silverbody in cool conditions, reflecting heat radiated by the body back into the body. A trash bag would not work as well in cool conditions, as it would absorb heat from the body and radiate it away into the environment."

Describe what you found confusing from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically identify the concept(s) that you do not understand.
"The science used to create the products use technology that I am not familiar with. It would be beneficial to understand what causes the products to either cool things off and/or insulate."

The primary heat transfer process that the Cooper Cooler™ uses to chill beverages is:
 conduction. ********************** [22] convection. ************************** [26] radiation. ** [2] (Unsure/guessing/lost/help!) ******* [7]

How plausible do you think these claims for the Cooper Cooler™ are?
(Only modal responses shown.)
"The Cooper Cooler™ can chill a soda in one minute": somewhat plausible [42%]
"Because it's spinning and not shaking your carbonated beverages, you don't have to worry about them exploding": somewhat plausible [35%]

The primary heat transfer process that the Coffee Joulies™ uses to moderate and maintain coffee temperatures is:
 conduction. ****************************** [30] convection. **************** [16] radiation. ****** [6] (Unsure/guessing/lost/help!) ***** [5]

How plausible do you think these claims for Coffee Joulies™ are?
(Only modal responses shown.)
"One 'bean' for every four ounces of coffee cools right down to 140° in a few seconds": somewhat plausible [33%]
"Keeps coffee at 140° for two full hours": not very plausible [37%]

The primary heat loss process that any blanket (regardless of type) should prevent in typical "emergency survival conditions" (on Earth) is:
 conduction. ********* [9] convection. ********** [10] radiation. ******************************* [31] (Unsure/guessing/lost/help!) ******* [7]

How plausible do you think heavy-duty garbage bag material will be just as effective as a space blanket for typical "emergency survival conditions" on Earth?
 Implausible. ****** [6] Not very plausible. ********** [12] Somewhat plausible. ******************** [20] Very plausible. ********* [9] (Unsure/guessing/lost/help!) ********** [10]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"The Coffee Joulies™ become liquid because they are absorbing heat, but then they give back that energy and become solid again?" (Yes.)

"Cooper Cooler™ could chill my wine and get me drunk much faster."

"I don't understand who needs a Cooper Cooler™--I feel like it's one of those appliances like a pizza maker which only has one use and better alternatives."

"How would the carbonated drink will not explode from spinning and not being shaken?" (Sounds like an experiment that just has to be done.)

"How expensive are we talking for the Coffee Joulies™? I was gonna ask for a printer for Christmas but those beans just made it to the top of the list." (Before you decide what to ask for this Christmas, get your science on in laboratory with the Coffee Joulies™.)

"Garbage bags are the obvious choice, you can use them to dispose of waste or as a blanket in an emergency situation. Take that science!" (Bam! Pow!)

"I am wondering how true these claims are and if my guesses were correct."

"What do you recommend we do in order to prepare for the final next next week?" (Look through the sample problems in the Final Exam study guide, and the equations on the sample Final Exam cover sheet.)