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 on applications of Newton's laws.
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.
"The problems for Newton's laws were a lot more conceptual than the projectile motion problems. You have to think about what forces act on each other and be very familiar with Newton's three laws."
"Friction force is interesting because it is almost always present, and when I used to play soccer, I would always consider how the grass would affect how far the ball rolled when it was thick compared to thin and short."
"That there are high points on surfaces that are invisible to our eyes, but are the cause of friction forces. The smoother the surface the less resistance."
"Honestly! If you want better traction in a rear-wheel drive car and the road, put something heavy in the trunk to increase normal force. I like real world/real situation examples."
"That when two objects are interacting with each other they have two forces working on them, which is the same force just looked at from opposite directions."
"I enjoyed learning about friction (still don't feel I have a full grasp on it). Learning about forces has really changed my perspective on terms such as weight and pull/push."
"The rules for friction were interesting. It was a challenge to do the free-body diagrams, but once I got the hang of them it was interesting to see the applications."
"That there are two different types of friction forces."
"Friction is caused by bonds between atoms that form between the 'high points' of the two surfaces that come in contact."
Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"I think I understand Newton's laws to a certain extent, but I still am not very confident in applying them to a variety of situations."
"I just lack confidence in drawing free-body diagrams and real-world applications because it is hard for me to put the formal information into a picture."
"The differentiation between sliding friction and static friction. I don't understand how static friction can become sliding friction if the friction does not prohibit sliding."
What is the meaning of the "normal" in the "normal force?"
"In geometry, 'normal' means 'perpendicular.'"
"'Normal' in 'normal force' merely means the force pushed on from one object resting on another. Its the 'regular' force that is pressed on one object to another."
The magnitude of the static friction force on an object that is being pushed, but is still stationary:
is zero. ***************** [17] is a constant, non-zero value. ********** [10] could have any value up to a maximum amount. ************************** [26] (Unsure/guessing/lost/help!) ******* [7]
The magnitude of the kinetic friction force on an object sliding at constant speed:
is zero. **** [4] is a constant, non-zero value. **************************************** [40] could have any value up to a maximum amount. ****** [6] (Unsure/guessing/lost/help!) ********** [10]
The magnitude of the kinetic friction force on a sliding object that is accelerating:
is zero. ** [2] is a constant, non-zero value. ********************* [21] could have any value up to a maximum amount. ************************ [24] (Unsure/guessing/lost/help!) ************* [13]
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Why are we learning this?" (Because this is a physics class.)
"Can you go over a homework problem in every class if we are not getting it, and to not just say that the answer is in the back of the book. It was really helpful when you did that last class session." (If the majority of the class reports having issues with that problem, and if time allows during the brief lecture period in class. Otherwise there will be time to individually go over homework problems during the group whiteboard problem-solving period at the end of every class.)
"In class last week you tried to explain weight force versus normal force. Can you go over that again?" (Weight force is the gravitational force of Earth pulling down on an object; it always has the magnitude w = m·g. normal force is a contact force exerted by a supporting surface; its magnitude can have any value ranging from 0 (surfaces not actually touching), any positive value (where the surfaces are being pressed into each other), up to a maximum value (where the surfaces can no longer support any greater force, and would begin breaking).)
"Can we go over problems relating to applying Newton's second law? Can we please go over the word problems as a class? I'd like to spend some time going over the examples." (Yes, yes, and as time allows.)
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