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 impulse and momentum.
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.
"How the elapsed time was presented made perfect sense to me in the presentation. Everything that wasn't suddenly stopped caused the object more damage opposed to the object being gradually slowed down to a full stop."
"The ping-pong ball and bowling ball example demonstrating how objects of different masses behave despite having the same velocity. Because Bill Nye is awesome."
"I think the physics behind the egg-splat example is interesting because I knew logically that the egg wouldn't splat after hitting the sheet, but I never understood why. Due to the greater stopping force, the egg that hits the wall splats. I never took into consideration the amount of time an object stops; it makes a lot of sense now!"
"I though that prolonging the impact of an impact of an object and how that affects it was interesting. How just making the object come to a stop slower 'saves' the object. It makes sense with the airbag, but it's crazy how a sheet can do that to an egg."
Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"In layman's terms, I would definitely think (and I assume others would as well) that an egg hitting a brick wall experiences a greater 'impulse' than when hitting a bedsheet. So, I'm just trying to wrap my head around it (of course)."
"I didn't find anything too confusing in this section. I also really enjoyed the online presentation for this portion. It laid things out very simply and effectively."
For the Bill Nye ping-pong ball versus bowling ball example, both balls are thrown with the same velocity. Which ball has greater momentum?
Ping-pong ball. * [1] Bowling ball. ********************************************** [46] (There is a tie.) ****** [6] (Unsure/guessing/lost/help!) ** [2]
For the eggs impacting a concrete wall and a hanging bedsheet with the same velocity, mark which egg has the greater quantity (or a tie).
(Only correct responses shown.)
Greater change in momentum ∆p: (There is a tie.) [46%]
Greater "impulse": (There is a tie.) [38%]
Longer impact time ∆t: egg hitting bedsheet : [84%]
Larger (net) stopping force ΣF: egg hitting concrete wall [72%]
For the crash-test dummies in cars crashing with the same velocity (without a seatbelt or an airbag, or with a seatbelt and airbag), mark which has the greater quantity (or a tie).
(Only correct responses shown.)
Greater change in momentum ∆p: (There is a tie.) [53%]
Greater "impulse": (There is a tie.) [40%]
Longer impact time ∆t: egg hitting bedsheet : [66%]
Larger (net) stopping force ΣF: egg hitting concrete wall [56%]
Briefly describe cause-and-effect relationship between impulse and momentum.
"The cause-and-effect relationship between impulse and momentum is that the initial-to-final change in momentum is caused by an impulse."
"An initial-to-final change in momentum (mass times velocity) is caused by an impulse (net force times elapsed time)."
"Impulse and momentum are inversely proportional."
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Why is the letter 'p' used to symbolize momentum?" (Momentum was originally referred to (improperly) as "impetus," which is derived from petere, "to go to.")
"I'm finding that I have to re-read the chapters several times before I can comprehend what it's saying. Physics is going to be a challenge for me this semester; it's very different from the science classes I've taken before." (I've also never been able to read a physics textbook chapter from start-to-finish. Treat it like an encyclopedia where the entries are not in alphabetical order, and are not indexed. By the time you know where to look up stuff, you probably understand it.)
"I do not like the flipped classroom style."
"When a third-grader was asked to cite Newton's first law, she said, 'Bodies in motion remain in motion, and bodies at rest stay in bed unless their mothers call them to get up.'"
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