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 temperature.
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.
"All of the railroad track examples. My dad works for Union Pacific and talks about this stuff all the time."
"That one could economically benefit from pumping gas at a certain time of the day because temperature directly effects the volume of gasoline that flows into the tank."
Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"I don't think anything was too confusing. This section was straightforward. I will probably have questions when we start working on it in class and get into the material more."
"That tracks are built in order to accommodate fluctuating temperatures. I don't understand how the length of the track is determined such that it does not expand or contract too much for the train to continue on the tracks."
For solids, what does α (Greek lowercase letter "alpha") in the linear thermal expansion equation stand for, and what SI units does it have?
"The linear expansion coefficient, unitless."
"Linear expansion coefficient, K-1."
"Coefficient of linear expansion; K-1 or °C-1."
Note the quantity (L/∆L) in for linear thermal expansion. What was this quantity called back in the context of elasticity?
"Elastic modulus."
"A fractional length change."
"Strain."
A square brass plate has a circular hole in its middle. How do each of the quantities change as the brass plate increases in temperature?
(Only correct responses shown.)
Width of the square plate: increases [73%]
Area of the square plate: increases [75%]
Diameter of the hole: increases [50%]
Area of the hole: increases [49%]
For solids, what is the mathematical relationship between the coefficient of volume expansion β and the coefficient of linear expansion α?
"α = (∆L)/L; β = (∆V)/V."
"They are both multiplied by ∆T."
"β = 3·α."
A tank contains a certain amount of gasoline at a cool temperature. How do each of the quantities change as the gasoline increases in temperature?
(Only correct responses shown.)
Mass of the gasoline: remains constant [79%]
Volume of the gasoline: increases [67%]
Density of the gasoline: decreases [62%]
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"I'd like it if when we're doing practice problems in class, we discussed more about why we chose the equation we chose. Most of the time it's just a brief mention, if there's any mention at all, and it makes the material practically impossible to understand when applying it to quizzes. Solving the equation is the easy part; choosing an equation in the midst of all the millions of equations we have to know is the hard part." (Yes, exactly. I'll try to do more of this, and if the choice of which equation is not obvious in solving a problem, please feel free to ask!)
"Do railroad tracks that buckle have to be replaced? Or do they revert back to their original form when the temperature cools?" (Even if the tracks had expanded less than their elastic limit, then they may not necessarily straighten out again when cooler, as they are fastened down to the buried railroad ties (or sleepers) buried in the ground, which may not shift back to their original positions.)
"Can we please go over practice problems in class?" (I'll try to do some example problems for you in class, and as always allocate 10-15 minutes at the end of class so you can ask me questions while you start on the assigned homework problems.)
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