20190819

Online reading assignment: speed and velocity

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 presentation on displacement, distance traveled, and average/instantaneous speed/velocity.


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.
"I understood the unit conversions very well. This may be because I have a large amount of practice from chemistry for unit conversions."

"I learned the differences between displacement and distance traveled and when to use them in certain situations. I also learned the formulas and how to calculate average speed average velocity and instantaneous velocity."

"Essentially, displacement acts as a measurement of the straight-line distance between point A and B while distance traveled encompasses all of the paths made outside of the straight line--or, how it got there."

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 understand the formulas like average speed is distance divided by time but doing more problems in class to make myself more familiar and less confused would be helpful. I am also slightly confused with the symbols."

"Making the full connection between average speed, and average velocity, has me confused some with the magnitude vector and using exact distance now how to use them correctly. I also am confused on how to use instantaneous velocity and speed correctly."

"At first, instantaneous velocity was confusing for me as it raised the question, "what value is deemed small enough--in both displacement distance and time--to be considered for the instantaneous velocity formula?" However, upon further reading--actually right under the formula in the slide--you state it would result in a value APPROACHING instantaneous velocity but not actually instantaneous velocity. Basically, the more precise stuff comes later. Possibly, way later. Maybe never. You tell me."

"Limits are confusing both in calculus and physics."

"There wasn't much confusing as I have taken a previous physics course."

Briefly describe how you would walk along a straight, level road such that your distance traveled would be longer than your displacement.
"If you were walking a straight line and walked back a couple of yards, then continued down the road, your distance traveled would be greater than your displacement."

"Distance could be greater than displacement, if you dropped something and had to return to pick it up and then continue in the original direction. Or possibly saw something interesting in the distance say to the right of travel direction, and walked over to see the mystical object and then continued back to the original direction. This would make the distance longer than the overall displacement value, I think?"

"Walk along straight road from initial starting point A to ending point B, but before reaching point B you turn around and walk towards point A. The total distance walked is greater than your displacement once you walk in the opposite direction."

"You would walk forward for a while then turn around or walk backwards."

In general, average speed will be __________ the magnitude of average velocity.
less than.   **** [4]
equal to.   **************** [16]
greater than.   ***************** [17]
(More than one of the above choices.)  ********* [9]
(None of the above choices.)   [0]
(Unsure/guessing/lost/help!)  ** [2]

In general, (instantaneous) speed will be __________ the magnitude of (instantaneous) velocity.
less than.   [0]
equal to.   ****************************** [30]
greater than.   [10]
(More than one of the above choices.)  *** [3]
(None of the above choices.)   [0]
(Unsure/guessing/lost/help!)  ***** [5]

In general, which of the following quantities could be negative?
Average velocity.  ************ [12]
Average speed.  [0]
(Instantaneous) velocity.   * [1]
(Instantaneous) speed.  [0]
(More than one of the above choices.)  ***************************** [29]
(None of the above choices.)   * [1]
(All of the above choices.)  *** [3]
(Unsure/guessing/lost/help!)  ** [2]

An odometer measures an object's:
displacement.   * [1]
distance traveled.  ********************************************** [46]
(instantaneous) velocity.   * [1]
(instantaneous) speed.  [0]
(Unsure/guessing/lost/help!)  [0]

A speedometer measures an object's:
displacement.   ** [2]
distance traveled.   [0]
(instantaneous) velocity.   ** [2]
(instantaneous) speed.  ******************************************** [44]
(Unsure/guessing/lost/help!)  [0]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
Is velocity the only quantity considered a vector?" (Of all the quantities we've considered so far (displacement/distance traveled, average velocity/speed, instantaneous velocity/speed), displacement, average velocity, and instantaneous velocity are all vectors, as they have magnitude and direction. Distance traveled, average speed, and instantaneous speed are all not vectors, as they only have (a positive) magnitude, and have no specified direction.)

"OH WAIT. I think it might be coming back to me from trigonometry. Is it that velocity is basically speed with a direction? It's pretty much speed with a direction, right? This is all confusing for me but perhaps it will make sense after class."

"I'm sorry If some of the answers are incorrect, I'm currently at a Starbucks and they're kicking us out due to it being close to closing time!"

"What is the difference between average and instantaneous speed?"

"Can you please review instantaneous speed versus velocity in class?"

"I just need more time with the instantaneous speed and velocity. The average speed and velocity I'm comfortable with."

"My question is in regards to the quiz questions on the main page. Will we be provided with conversion factors on quizzes and tests?" (Yes, as needed.)

"How do you handle quizzes with DSPS students? Since they are given at the beginning of class." (Arrangements would be made with DSPS to take the quiz before class. Midterms can be taken anytime the day of class.)

"Was the first week of school everything you ever dreamed of?" (Yes. But every first week of school is like that. What happens afterwards, well, that's a different story.)

"I feel like in physics where I struggled in the most what with over thinking when it came to anything with a number but what I found helped we was reading the chapter beforehand even if it was a glance or in class."

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