20120925

Online reading assignment: uniform circular motion

Physics 205A, fall semester 2012
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 uniform circular motion.

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.
"Although there are many circumstances such as a merry-go-round, spinning something on a string, or even driving a motorcycle in a circle, that the basic formulas and ideas of uniform circular motion stay the same."

"The direction of acceleration for uniform circular motion is inward, rather than outward, because I have always felt a pull outward."

"As long as the tires roll without slipping, there is no relative motion between the bottom of the tires and the road, so it is the force of static friction that acts."

"Why roads are banked. If not, I would have probably been in a few accidents by now."
Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"I'm having problems identifying the types of forces acting on objects, when told to draw a diagram."

"How does the acceleration go toward the center of the circle but the object is moving in a perpendicular direction, I just don't get that."

"I do not know how to explain tangential vs. radial direction."

"I kind of get the whole non-zero acceleration thing for uniform circular motion but I am still a little lost. I think my mind says if the speed is not changing acceleration should be zero."
Briefly describe the difference between the "centripetal" direction and the "centrifugal" direction.
"'Centripetal' = center-seeking direction; 'centrifugal' = center-fleeing direction."

"Centripetal is like radial, and centrifugal is like tangential."
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Can you provide us answers for the flashcards?" (As a matter of policy, answers to flashcard questions are not published nor released, but I would be more than willing to discuss your responses to flashcard questions that were not used in class, during posted office hours or an arranged appointment, just before/after lecture, or via e-mail.)

"Can we get a list of topics that will be on each quiz/test? Or at least a list of what sections from the book we need to know?" (The study guide for each quiz or exam is always posted on the course website.)

"Sometimes I feel like I understand the material really well, and then on quizzes/flashcard questions I just don't understand anymore. :(" (This is why flashcard questions are used in class, for both students and myself as the instructor to assess what you know, and what you only thought you knew (but we can subsequently spend more time on).)

"Doing the problems step-by-step in class is really helping me. The problem-solving is what I am having a harder time with rather than the definitions." (There is only so much time that can be set aside for step-by-step examples in class, but the student solutions manual for the textbook, with many worked-out answers, is on reserve in the library.)

"Well, why is...those things? (Because...physics.)