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.
"For uniform circular motion, the velocity vector is perpendicular to a radius drawn from the center of a circle to the position of the object, and I found that the animated *.GIF of the bowling ball and mallet clearly demonstrated that--it also shows that the speed of the bowling ball is constant, but you need to manipulate the direction of the force exerted on it to be centripetal."
That circular motion is obviously covered by Newton's second law, even when restricted to moving at constant speed along a circle."
"There was nothing interesting this time."
"That an object that is traveling in a uniform circular path will have an acceleration directed toward the center of the circular path."
"In uniform circular motion the acceleration is constant in the magnitude, but with nonuniform circular motion the acceleration changes as the speed is changing."
"That the net force for uniform circular motion must point in the inward direction. I originally assumed that it would point outwards, or that it would be in the actual direction of the circle."
Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"I didn't really think the car arcing over the top of the hill was circular motion. I thought of it as a parabola, but I guess a parabola has a half-circle shape."
Will definitely need help applying most of this in tomorrow's class. Explanations and corrections are, in my case anyway, very necessary."
"I was having trouble identifying which direction the net force would be on the 'picto-quiz' examples."
"I don't understand how something in non-uniform circular motion can "momentarily" experience uniform circular motion."
"I do not understand how to use the net force equation for uniform circular motion."
Match the motion of an object with the applicable Newton's law.
(Only correct responses shown.)
Constant speed along a straight line: Newton's first law [95%]
Speeding up along a straight line: Newton's second law [85%]
Slowing down along a straight line: Newton's second law [89%]
Constant speed along a circular path: Newton's second law [54%]
Speeding up along a circular path: Newton's second law [93%]
Slowing down along a circular path: Newton's second law [97%]
Match the circular motion directions with their descriptions.
(Only correct responses shown.)
Along the velocity vector: tangential [51%]
In towards the center of circle: centripetal [71%]; radial [17%]
Sideways to the velocity vector: radial [34%]
Out away from the center of the circle: centrifugal [62%]
Net force on an object undergoing uniform circular motion: centripetal [44%]; radial [29%]
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Can you just teach the reading material in class, and we solve problems at home?" (I've seen how you do your homework in class. Believe me, you want to do your homework in class where I'm available to help you. Also, I already go over some of the reading material in class, on selected concepts you collectively are struggling with (and I do appreciate your feedback on the online reading assignments to know what these difficulties are when I plan my mini-lectures the night before class).)
"I would really like it if we could go over a few uniform versus non-uniform circular motion examples. Feeling a little shaky about this section." (As you wish. (Note: we will only consider uniform circular motion; or non-uniform circular motion that is momentarily uniform circular motion in nature.)
"Can you go over the circular motion directions?" (See the above results on this blog post. The direction labels are basic nomenclature and definitions you just need to get familiar with.)
"I would benefit greatly from the correct answers to the reading assignment survey questions. If there is a way to see them, please let me know. Thanks." (This blog. The blog that I show you at the start of every class: http://waiferx.blogspot.com.)
"How does our lab grade affect our overall grade in the class?" (From the course policy, lab is 100 points out of the total of 700 points for this course. Each whole letter grade is worth 100 points.)
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