20190821

Online reading assignment: motion

Physics 205A, fall semester 2019
Cuesta College, San Luis Obispo, CA

Students have a bi-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 the reading textbook chapters and previewing a flipped class presentation on (constant acceleration) motion.


Selected/edited responses are given below.

Describe what you understand from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically demonstrate your level of understanding.
"Using derivatives and integrals to move left or right on the chain of pain, respectively."

"From what I was able to deduce, the reading is about the relationship between acceleration, velocity, and motion. When you follow the charts given they show their relationship by tangents and chords (and areas)."

"The concept of acceleration--how it correlates to what we've already learned with velocity and displacement. With a positive acceleration headed in the same direction as the velocity, the velocity increases, resulting in the object moving faster. However with a negative acceleration pointed in the opposite direction, the object slows down resulting in a smaller velocity."

Describe what you found confusing from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically identify the concept(s) that you do not understand.
"I think the kinematic equations were a lot to process. It made sense, but I need to get more familiarized with them."

"I don't understand how chord slopes work and what information it is telling me. I also don't get what number would be the chord slope."

"The graphical relations are confusing at the moment but will hopefully be clarified once I see some of these graphical relations in action. When I'll need to use what equation will take some studying."

"I don't fully understand the operations that are embedded in our non-calculus 'chain of pain.' I'm confused on how they all connect."

"Memorizing all the equations. I have little practice or interactions with these equations and the key to learning it would be to have a visual connected with every part of the equation so I can learn by logic and not memorization. Also lost on the slopes."

Briefly describe the difference(s) between a chord slope and a tangent slope on a graph.
"A chord slope is a straight line that connects two points on a curve. A tangent slope touches the line at only one point."

"A tangent line is slope of a line from a single point on a curved line and a chord slope is the line between two points on the curve."

"Chord slopes are for average values and tangent slopes are for instantanious."

"I honestly don't understand these concepts enough to explain."

Mark the level of your exposure to (basic calculus) concepts of derivatives/integrals.
None at all.   ********** [12]
Slight.   ******* [7]
Some.   ******** [8]
A fair amount.  ************* [13]
A lot.   *** [3]

Indicate how each of these quantities are determined from kinematic graphs.
(Only correct responses shown.)
Displacement ∆x: area under a vx(t) graph. [58%]
Position x: (None of these choices.) [40%]
Change in (instantaneous) velocity ∆vx: area under an ax(t) graph. [51%]
(Instantaneous) velocity vx: tangent slope of an x(t) graph. [65%]
Average velocity vx,av: chord slope of an x(t) graph. [60%]
(Instantaneous) acceleration ax: tangent slope of a vx(t) graph. [56%]
Average acceleration ax,av: chord slope of a vx(t) graph. [58%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"What is the most important thing to understand from this homework?" (Knowing what to do with a graph, and how to do it (calculating areas, chord slopes, or tangent slopes, i.e. the "chain of pain").)

"I'm a little confused on when to use m/s and m/s2. Is m/s used only with velocity and m/s2 only with acceleration?" (Yes.)

"Why have a chart that sounds and looks torturous?"

"The chain of pain is so daunting at first but if you stare at it long enough it kind of starts to make sense, as long as you can see the system and you know the variables."

"I am finding the 'chain of pain' very confusing. Can you please lecture on this in class."

"I'm confused by 'vav,x.' Is that the average velocity based off of the displacement value of x?" (Yes, it is the average horizontal velocity.)

"Will we be making or looking at graphs during the next lab?" (Yes, next lab will be an introduction to graphs in general (using Excel), and the following two labs will have you generating velocity versus time graphs generated from video tracking software, or from ultrasound motion detectors.)

"Do we have to memorize all these formulas and the kinematic graphs?" (All of the equations will be given to you. However, the relationships between the graphs (areas, chord slopes, and tangent slopes, i.e. the "chain of pain") is something you have to memorize yourself.)

"How do you solve kinematics equations that have more than one missing variable? Would you use substitution?" (Yes. You would need as many equations as you have missing variables.)

"This class is beginning to concern me."

"Hopelessly lost :("

No comments: