20130929

Online reading assignment: work

Physics 205A, fall semester 2013
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 work.

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.
"I'm still kind of processing it all, but I thought it was interesting that work was a scalar without direction. I just would have thought that it would have mattered because we use direction for certain force calculations (acceleration for example)."

"I found the law of conservation of energy to be very interesting in that the total energy in the universe is unchanged by any physical process and that during a reaction the total energy before equals the total energy afterwards."

"Already knowing about physics, makes this class easier and finally taking the time to read the textbook makes everything more interesting."

"I find it interesting how there are so many different forms of energy. No one really thinks about the many forms, especially in everyday life."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"I'm confused about the examples. I understand where the transfers are happening, but not how we put it into a calculation. I think I just need to see some examples in lecture."

"I had a hard time with figuring out how work could be positive, zero, or negative."

"I'm confused when calculating work when force and displacement are parallel."

"I was not confused on any of this material."

"It all seemed to make sense."

Match the amount of work exerted by these forces on an object.
(Only correct responses shown.)
Pushing along the direction of motion: positive [82%]
Pushing against the direction of motion: negative [66%]
Pushing sideways to the direction of motion: zero [64%]
Pulling such that the angle between the force and motion is an acute angle: positive [82%]
Pulling such that the angle between the force and motion is an obtuse angle: negative [66%]

State the SI unit for work, and describe how the work SI unit is related to the force SI unit.
"The unit for work is Joules, which is N × m. It is essentially how much force (N) is applied over a distance (m)."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Can I pay somebody to do this?" (*smh*.)

"Will we review trigonometry at some point?" (We already reviewed all the trigonometry you need to know.)

"The blog lectures are very visual which helps me and they are interesting."

"Can we please have lectures before reading the material at home? Can you do problems on the board? The flipped classroom is a nice idea but I think me and other classmates are finding it difficult to use." (When you (attempt to) read the textbook before you come to class, yes, I know you're confused, but by telling me in the online reading assignments specifically what you're confused on, I know which "muddiest points" I should hit on in lecture.)

"Would an opposite force applied to a moving object (kinetic friction) be negative work because it's slowing/is against the direction of motion?" (Yes. But also mathematically because the cosine of 180° (the force and the motion are opposite directions) is -1.)

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