20131112

Online reading assignment: simple harmonic motion

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 simple harmonic motion.

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.
"It is interesting to me that mass doesn't seem to effect the simple pendulum period. I always thought that a greater mass would swing more slowly."

"I really enjoyed the textbook discussion of walking as being similar to a pendulum swinging. It's something that I've both never noticed or considered. I'm definitely gonna be paying attention to that for the next few days."

"The human slingshot in the presentation seemed pretty cool but other than that this section wasn't too intriguing."

"The pendulum, because 'The Pit and the Pendulum' is one of my favorite Edgar Allen Poe stories."

"I found it easy to understand when the book said that the word 'simple' in SHM means that the amplitude of the vibration is constant."

"That simple harmonic motion can be applied to uniform circular motion. The position and acceleration of a pin moving in a circular motion, in SHM can be found using sinusoidal functions."

"Nothing."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"I don't understand rationally why an object with a greater mass would not swing back-and-forth more slowly (unless it would only effect the period of time because of air resistance)."

"I got lost with analyzing simple harmonic motion with energy conservation."

"Nothing was too bad."

"I don't really understand the pendulum period equations. I understand how to solve using the equation, but I don't fully understand when to use which (the one focused on mass or the one focused on length). The GIF animations really help, but I think I need to read more about this in the book."

For simple harmonic motion of a mass on a spring, classify each of these parameters are being "independent" (able to be changed without affecting other independent parameters), or "dependent" (will be changed if (other) independent values are changed). Ignore friction/drag.
(Only correct responses shown.)
Spring constant k: independent [68%]
Mass m : independent [68%]
Amplitude A : independent [42%]
Period T : dependent [74%]

For simple harmonic motion of a simple pendulum (point mass on a string), classify each of these parameters are being "independent" (able to be changed without affecting other independent parameters), or "dependent" (will be changed if (other) independent values are changed). Ignore friction/drag.
(Only correct responses shown.)
String length L: independent [68%]
Mass m : independent [72%]
Amplitude A : independent [52%]
Period T : dependent [84%]

Why do the K and U graphs in Fig. 10.20 (p. 374) always have positive values?
"These values are always positive."

"Because negatives don't make sense in those values."

"Because you don't ever have negative energy."

"Because the mass and spring constant are positive numbers, and you could have a -x (displacement) depending on the direction but it is squared, making it a positive number. The velocity is also squared, making it a positive number as well."

"You either have some energy or none at all, there is no 'negative energy.'"

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"This course is pretty hard to grasp but I'm getting better and better at it."

"What is the restoring force for a mass-spring system?" (The force of the spring that pulls or pushes an object back to its equilibrium position.)

"I found the graph interpretations as well as differentiating between dependent and independent perimeters to be difficult. I could use an explanation on these to better understand the concept of harmonic motion." (Yes.)

"I'm scared for the midterm."

"Looking forward to your lecture on this. I normally feel pretty shaky going in, but you seem to always find a way to make the topic simple and understandable!"

"I'm really enjoying your class, I had a horrible teacher in high school and I was really nervous about taking this again, but it's one of my favorite classes! Thanks!"

No comments: