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Online reading assignment: free fall

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 free fall.

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 find physics to be pretty interesting in general, but this didn't really offer much pizzazz."

"The acceleration is always downward even if the object is moving upwards, because of Earth's gravitational pull pulling is down. This is the opposite of what you would expect, but it makes sense."

"When considering objects in free fall, it's very interesting that the highest point will give zero velocity but not zero acceleration."

"Free fall. The world is making slowly making sense to me."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"For me, its a matter of keeping all of the formulas in order, and using each one in the correct instance. There are just an abundance, and though it will take some practice, I'll get it straight in time."

"The free fall velocity versus time graphs."

"I do not understand how at the highest point that the acceleration is not also at zero like the velocity."

"The assumptions we make about drag after only reading the textbook, since the book didn't go into any detail on this topic that I could find. However, this was all cleared up after reading your blog."

"Using -9.80 m/s2 for the value of an object in free fall. I don't understand why the negative sign is applied to the value. Also what does it mean to say free fall is motion with constant acceleration?"

"I don't understand how something thrown downward is considered free fall."

"The relationship between acceleration and velocity confused me until I was able to see in graphical form, then it made much more sense to me."

"I had trouble understanding the graphs and how they were created."

"The equations are confusing to me because there seem to be so many variables all squished together, and I look at it and instantly don't know what to do with them."

Explain what assumptions are made about the amount of drag (air resistance) on an object said to be in free fall.
"We assume that there is none."

"The assumptions made about air resistance on an object in free fall being zero are ideal. There is always some air resistance."

For all possible cases of an object during free fall, ay =
+9.80 m/s2.   ******* [7]
0.   [0]
-9.80 m/s2.   ******************************* [31]
(More than one of the above choices.)   ***** [5]
(Unsure/guessing/lost/help!)  ** [2]

For all possible cases of an object during free fall, the distance traveled will be __________ to the magnitude of the displacement.
less than.   [0]
equal to.   ************** [14]
greater than.   ** [2]
(More than one of the above choices.)   **************************** [28]
(Unsure/guessing/lost/help!)  * [1]

For all possible cases of an object during free fall, the magnitude of the average acceleration will be __________ to the magnitude of the instantaneous acceleration.
less than.   **** [4]
equal to.   ***************** [17]
greater than.   ***** [5]
(More than one of the above choices.)   ********* [9]
(Unsure/guessing/lost/help!)  ********** [10]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"After having a couple weeks to get used to the flipped classroom I'm starting to really see the benefits and it is actually helping me learn a lot more."

"Still trying to get a copy of the text." (*smh*.)

"This section is more clear than the previous one and should be given less attention than the homework."

"Help. Completely lost and need more notes and lecture. Where should we find extra help if we need it?" (Diagnosis: confusion. Prescription: see me in office hours (or make an appointment). Prognosis: fair to good. Results may vary.)

"For all possible cases of an object during free fall, the distance traveled will be equal or greater than displacement? I think this because if something is dropped rather than tossed upward, wouldn't the distance traveled equal the displacement; and in all other instances the distance traveled would be greater than displacement, since its traveling up then back down." (Yes. Exactly.)

"Going over the real-life scenarios to differentiate free fall versus those that are not, would be helpful." (We will definitely do that in class; and relate those free fall cases to the velocity versus time graphs, and also understand why the (instantaneous? average?) acceleration at the highest point cannot be zero.)

"That *.gif animation at the beginning of your blog entry for this lesson is crazy! I kept on watching it over and over."

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