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 temperature.
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.
"The increase in any one dimension of a solid is called linear expansion. The volume of a normal material also increases as temperature increases, this is known as volume thermal expansion."
"The material-dependent linear expansion coefficient characterizes the response of the material to thermal stress."
"The material in the section relate to experiences in real life, such as liquid expanding when it is cooled and metals cooling and expanding."
"Solids and liquids expand with changes in temperature. A shorter length rod will expand less than a longer length when made of the same material and same change in temperature. ∆L is the change in length due to temperature."
"Thermal stress causes strain. A shorter beam will require a greater change in temperature to expand/contract the same distance as a longer beam."
"I learned that I need cooler gas to save money at the pump."
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 don't fully understand volume expansion and feel that in some of the equations I would go go back and forth on what increases or decreases in volume."
"I found thermal stress and strain confusing. I could use further explanation on the equation."
"How you would calculate the amount of expansion that a metal undergoes by given the original length and the temperature?"
"I do not know how all of the equations relate to each other. I think I will have to review more before next class."
"Not as confusing as the last few subjects. Which is a relief for the end of semester. Still, I skimmed it because I'm studying for the quiz."
"Could you go over thermal stress? Maybe do an example problem, the one in the book was a little confusing."
"I didn't understand why the shorter beam will require a greater increase in temperature to expand the same amount as the longer beam."
"Thankfully due to my chemistry class this wasn't very confusing."
"I found most everything confusing from this reading and would benefit greatly from in class examples."
"I haven't gotten much into the reading yet, so it's all a little confusing right now."
"Nothing."
For solids, what is the mathematical relationship between the coefficient of volume expansion β and the coefficient of linear expansion α?
"β = 3·α."
"They have the same units, K–1."
"No idea."
a smaller. *********************** [23] the same. **** [4] a larger. ****** [6] (Unsure/guessing/lost/help!) * [1]
less than. ********************** [22] equal to. ***** [5] greater than. ***** [5] (Unsure/guessing/lost/help!) ** [2]
less than. ************* [13] equal to. **** [4] greater than. ************ [12] (Unsure/guessing/lost/help!) ***** [5]
(Only correct responses shown.)
mass: the cool gallon [38%]
density: the cool gallon [68%]
Briefly explain why a gallon of gasoline purchased when it is cool would be better than a gallon of gasoline purchased when it is warm. (In either case, the fuel company dispenses the same volume of exactly one "standard" gallon.)
"I don't know. Is it easier to handle? Maybe cheaper to move."
"The cooler gallon of gasoline would have more density and therefore should have more energy based in that gallon of gasoline."
"Because it has a greater density so the amount of energy within that gallon of gasoline is greater."
"The gasoline is more dense when it is cold and there for the volume is smaller. Although when it is warm the volume is bigger due to it being less dense. The volume might be more but the amount is still the same. Gas stations measure by volume therefore it is better to get gas when it is cold."
"Gasoline (and nearly all objects) expand and become less dense due to heat. Because of this it is more dense during a cool day. Since its density increases and since gas is bought in volume, you get more 'bang for your buck' when you buy on a cooler day."
"How can we figure out the gasoline question? We weren't given the properties of gasoline and how reactive it is at different temperatures."
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Thank you for applying concepts to real-life situations."
"Does heat by itself change the atomic structure in solids?" (The space between atoms increases as atoms vibrate more at higher temperatures, because atoms repel each other at close distances, they will spend more time farther apart than closer together as they vibrate more.)
"We will soon be fluent in Greek." (Graecum est; non legitur.)
"Still really enjoying the class."
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