20171211

Online reading assignment: heat transfer applications

Physics 205A, fall semester 2017
Cuesta College, San Luis Obispo, CA

Students have a bi-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.
"I think the examples provided that show how heat can be applied helped leaven my understanding a bit. I think the best example for me was the 'Coffee Joulies' example because it reminds me a lot of the examples used in the last chapter. Unfortunately I have not yet given myself enough time at look at the textbook."

"That companies try and make products that transfer heat in order to try and make money."

"There are a lot of companies attempting to create products to inhibit or change temperature of objects."

"I learned what we will be doing in lab next week. We will be choosing which claim we will investigate, either testing the cooper cooler method, the coffee joulies method, or the space blanket."

"All of these applications seem really interesting. The most interesting was probably the insulation blanket since that has real world applications that could quite literally save some lives during snowfall. Granted, you would need pants and a jacket."

"There are several different technologies that have been created to either heat something up or cool something down. These consumer products claim to use innovative techniques."

"Examples of conduction, convection, and radiation were shown. The 'Cooper Cooler' is supposed to cool beverages via convection, 'Coffee Joulies' are supposed to cool and maintain coffee temperature at 140° F, and a space blanket is supposed to keep one warm by trapping and reflecting heat back to the user."

"I understand the idea of heat transfer, the different types of heat transfer, and energy transfer in this chapter. The various examples that we went over in class last Monday were very helpful in solidifying my understanding."

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.
"I'm still a little confused on the difference between convection, condition and radiation. I think I would benefit from some in class examples."

"I found the 'Coffee Joulies' to be confusing on how they work."

"Conduction vs. convection."

"Not very confused. Convection is the most difficult of the three heat transfers, though."

"Not much, it's mostly chemistry review."

The primary heat transfer process that the Cooper Cooler™ uses to chill beverages is:
conduction.  *************** [15]
convection.  ******************* [19]
radiation.  * [1]
(Unsure/guessing/lost/help!)  * [1]

How plausible do you think these claims for the Cooper Cooler™ are?
(Only modal responses shown.)
"Chills beverages on demand forty times faster than a freezer" : somewhat plausible [50%]
"Because it's spinning and not shaking your carbonated beverages, you don't have to worry about them exploding" : not very plausible [33%]

The primary heat transfer process that the Coffee Joulies™ uses to moderate and maintain coffee temperatures is:
conduction.  *********************** [23]
convection.  *********** [11]
radiation.  * [1]
(Unsure/guessing/lost/help!)  * [1]

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° F in a few seconds": somewhat plausible [47%]
"Keeps coffee at 140° for two full hours": not very plausible [50%]

The primary heat loss process that a reflective space blanket is intended to minimize is:
conduction.  ******* [7]
convection.  ***** [5]
radiation.  ********************** [22]
(Unsure/guessing/lost/help!)  ** [2]

How plausible do you think these claims for a space blanket are?
(Only modal responses shown.)
"It reflects your body heat back to you" : somewhat plausible [67%]
"You still must have insulation between you and the blanket to minimize conductive heat loss" : very plausible [47%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Is a practice final being posted or done in class?" (It's already posted under the "Final Exam" goals page.)

"Is it possible to have the correct answer of the first problem from the last midterm?" (It's already been posted under the "Midterm 2" goals page.)

"When did you say the grades would be updated before the final? Was it this coming Friday?" (This coming Saturday. However, your lab grades may not include the last few assignments, but that will be noted if that happens.)

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