Online reading assignment: heat transfer applications

Physics 205A, fall semester 2015
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 understand conduction, convection, and radiation pretty well now."

"That we will be choosing one of these products to test in lab."

"People will say just about anything in hopes of selling a product, whether it is true or not. And that the properties of heating and cooling objects are much simpler to understand when put into situations involving food. I like food."

"I understand that we will be testing different claims by companies that provide goods for the consumer. The challenge is for us to decipher whether these claims are plausible or not."
"I don't know. The presentation never gave me any facts, just questions."

"I understand that the need for bevergaes to be the perfect drinking temperature is paramount. The main methods used to obtain this optimum temperature utilize conduction--the transfer of heat from warm objects to cooler ones through physical contact."
"There are different products that have been made that take advantage of the various heat transfers. However, not all of the products are efficient as they claim to be."

"The presentation preview made a few claims about different products that are supposed to heat or cool different products at a faster speed than they would naturally. The claims seemed to work by making the particular thing reach thermal equilibrium with whats being put in it or on it (like the 'stones' in the coffee)."

"The Cooper Cooler™ is able to chill beverages much quicker than a freezer or a refrigerator (90× faster than a refrigerator and 40× faster than a freezer)."

"I learned some new material reading the presentation, especially about the coffee joulies. It's interesting how they absorb the heat from the coffee and as it begins to cool down it releases more heat keeping it at a constant until the heat is out."

"A space blanket works in a cool conditions, which it reflects heat radiated by the body back into the body."

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.
"How those coffee beans could keep the coffee warm for 2 hours. I am very skeptical of this. I would like to know more about the physics involved here."

"This was just kind of review."

"I don't think I found anything that confusing really."

"I find most things in physics confusing."

"I was a little confused about which form of heat transfer was responsible for the temperature change in each scenario. I can't decide if the Coffee Joulies™ would cool through conduction or convection, for example."

The primary heat transfer process that the Cooper Cooler™ uses to chill beverages is:
conduction.  ************************ [24]
convection.  **************************** [28]
radiation.  ** [2]
(Unsure/guessing/lost/help!)  **** [4]

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 [52%]
"Because it's spinning and not shaking your carbonated beverages, you don't have to worry about them exploding": somewhat plausible [40%]

The primary heat transfer process that the Coffee Joulies™ uses to moderate and maintain coffee temperatures is:
conduction.  *********************************** [35]
convection.  ************** [14]
radiation.  ****** [6]
(Unsure/guessing/lost/help!)  *** [3]

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 [52%]
"Keeps coffee at 140° for two full hours": not very plausible [34%]

The primary heat loss process that any blanket (regardless of type) should prevent in typical "emergency survival conditions" (on Earth) is:
conduction.  ********** [10]
convection.  **** [4]
radiation.  ***************************************** [41]
(Unsure/guessing/lost/help!)  *** [3]

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.  ********* [9]
Not very plausible.  ************* [13]
Somewhat plausible.  ************* [23]
Very plausible.  ********* [9]
(Unsure/guessing/lost/help!)  **** [4]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"How does spinning not induce CO2 formation the way shaking does in a soda? How do the Coffee Joulies™ cool the drink immediately to 140° F?"

"Coffee Joulies™? I mean, if you don't drink your coffee by the time it's room temperature, you're doing something wrong."

"I am itching to go snowboarding!" (Just don't be one of those snowboarders that sits down in the middle of the run for a smoke break. I hate those guys.)

"Found this chapter to be very understandable--can we add some conceptual dialogue to these question for class tomorrow?"

"Can we go over these in class? I really have no idea if I'm doing these even remotely correct."

"I found a kitten in the dumpster and decided to keep him. I guess you can call me Captain America now." (That, or a dumpster diver. Captain Dumpster Diver. #iwillhughimandpethimandsqueezehim #andiwillnamehimgeorge)

"I secretly can't wait till the holidays are over. I want to commit to my regular eating and workout schedule again." (#goodgradesgoodsleepgoodhealth #chooseonlytwo)

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