## 20120917

### Online reading assignment: forces and 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 forces and 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.
"An object can have a net force of zero even when it is moving."

"No force is required to keep an object in motion if there are no forces opposing its motion. I find this statement interesting because on Earth, there is always some sort of force opposing an object, so to think that an object could go on forever without any force is incredible."

"How Newton had build so much on the works of others to form his laws."
Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"How some of the laws are applied to different problems, but I think it will make more sense once you explain it in class."

"The notation of Newton's second law is confusing. The symbols are new to me."
Explain what would be the minimum (non-zero) number of forces acting on an object, such that the net force could be zero.
"Two forces acting on an object on opposite sides with equal force."

"Three, because in order for all the forces to cancel out on a graph, the tip of the last vector must end up at the tail of the first one."

"The net force could be zero with a minimum of one force acting upon the object which would be the velocity of that object.

"I can't answer this. It confuses me."
Describe the motion of an object that is moving, yet has a zero net force exerted on it.
"An object moving at a constant speed with no acceleration."

"Traveling in a straight line for eternity."

"It isn't moving...right?"
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"I couldn't think of a way that an object would have a zero net force upon it in a real-world example, wouldn't you need to be in a vacuum?" No necessarily, but the situation would have to be carefully designed to be as ideal as possible.

"Are the reading assignments graded on completion or correctness? Because I get very confused trying to sort out all of the information I read in the text, and would usually like some clarification in class about the questions asked." Graded for completion, as long as there is a demonstrated effort towards reading and comprehending the material.

"Are we always going to go this fast? Seems like a lot of complex material going by quickly." For the most part, yes. However, these reading assignments are intended to elicit feedback on the comprehension (or lack thereof) of material before coming to class, in order to adjust the level of instruction in class.

"The in-class flashcard questions are really helping me."