20141022

Online reading assignment: stellar parameters (SLO campus)

Astronomy 210, fall semester 2014
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 presentations on parallax, distance, apparent magnitude, absolute magnitude, Wien's law and the Stefan-Boltzmann law.


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.
"That we are able to find out the size of a star based upon its luminosity and temperature."

"Wien's law is neat because you can tell how hot a star is by just looking at what color it is."

"The H-R diagram--because this gives you an idea of how big, how hot, and how other stars are related to the sun."

"White hot stars are hotter than the red ones."

"I never knew that there was this much information on stars. I'm totally interested but I'm totally confused at the same time."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"Pretty much everything."

"The differences between apparent and absolute magnitude."

"How to calculate distance and brightness! Oh my gosh, help!"

"The S-B Law because I just don't understand how it works."

"The stars and all of their classifications! After the video [Wonders of the Universe: Stardust] last week, I became aware of how much there is to know about stars and I was blown away. And I knew this was going to trip me up. So just all the information and keeping it straight is the hardest part."

Explain how apparent magnitude and the absolute magnitude are defined differently.
"Apparent magnitude is how bright a star looks like from the naked eye and absolute magnitude is how bright a star really is (once the distance of the star is accounted for)."

"Apparent magnitude is how bright we see a star, regardless of its distance from the earth. Absolute magnitude is how bright a star would appear if we put it at 32.616 light-years [10 parsecs] away."

"I'm unsure."

"Apparent is a guesstimate, and absolute is exact."

Suppose the sun was moved to a distance of 10 parsecs away. As a result, its __________ magnitude would become dimmer.
absolute.  ********* [9]
apparent.  ******************* [19]
(Both of the above choices.)  ***** [5]
(Neither of the above choices.)  [0]
(Unsure/guessing/lost/help!)  **** [4]

Rank the temperatures of these stars (1 = hottest, 4 = coolest; there are no ties).
(Only correct responses shown.)
Hottest: blue main sequence star [81%]
Second hottest: white main sequence star [76%]
Third hottest: yellow main sequence star [84%]
Coolest: red main sequence star [92%]

Rank the temperatures of these stars (1 = hottest, 4 = coolest; there are no ties).
(Only correct responses shown.)
Hottest: blue supergiant [78%]
Second hottest: white dwarf [51%]
Third hottest: yellow supergiant [64%]
Coolest: red dwarf [87%]

Two stars (equally far away) have the same temperature, but one star is dimmer, and the other star is brighter. The __________ star will be larger in size.
dimmer.  ****** [6]
brighter.  **************************** [28]
(These stars would be the same size.)  [0]
(Unsure/guessing/lost/help!)  *** [3]

Two stars (equally far away) have the same brightness, but one star is cooler, and the other star is hotter. The __________ star will be larger in size.
cooler.  ********************* [21]
hotter.  ********* [9]
(These stars would be the same size.)  **** [4]
(Unsure/guessing/lost/help!)  *** [3]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"More examples and charts would be good. Please go over the distance of the stars and what is cooler/hotter and dimmer/brighter." (Yes.)

"Parsecs (pc) are better than light-years (ly)!" (Yes.)

"Do we need to memorize all of these equations?" (What equations? More seriously, you do need to "memorize" the logical reasoning behind the mathematics we'll be learning this week in order to apply it to quiz and exam questions.)

"What are you going to be for Halloween?" (Come to Madonnaween at the Madonna Inn the Monday before Halloween, and find out. I'm not dressing up as a DJ, but I am DJing!))

Online reading assignment: torque and rotations

Physics 205A, fall semester 2014
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 torque and rotations.


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.
"Torque is the twisting by a force that tends to cause rotation."

"Torque is the product of force (N) and the length of the perpendicular lever arm (m). The force vector (line of action) is perpendicular to the perpendicular lever arm."

"N1 applies to torque when the object is in equilibrium. N2 applies when the object is starting to rotate."

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.
"Net torque."

"How an object can have a net force of zero while the torque is nonzero. I also do not get how if its torque was nonzero and net force was zero, how such an object could have a nonzero angular acceleration."

"I am not 100% on drawing out a diagram for torque."

"Line of action for a force."

"The lever arm, and how it was drawn/what function it serves."

What is the SI (Système International) unit for torque?
"N·m."

"Tau."

"Newtons."

Briefly describe how the line of action should be drawn for a given force.
"The line of action should extend along the force vector direction."

"I have no idea."

"With a dashed line."

When a lever arm (or moment arm) is drawn, briefly explain where it starts, and how it should intersect the line of action for a force.
"The lever arm starts at the rotation axis and is perpendicular to the line of action."

"I have no clue. Sorry."

For the stuck wrench (assuming that it is rigid and not flexing), Newton's rotational __________ law applies, and the clockwise torques and counterclockwise torques acting on the wrench are __________.
first; balanced.   ************************************************* [49]
second; unbalanced.   ********* [9]
(Unsure/lost/guessing/help!)   ***** [5]

For the crane, Newton's rotational __________ law applies, and the clockwise torques and counterclockwise torques acting on the crane are __________.
first; balanced.   ******** [8]
second; unbalanced.   ************************************************* [49]
(Unsure/lost/guessing/help!)   ****** [6]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"I once broke a torque wrench trying to loosen the lug nuts on a Lexus. They must have been torqued up to 200 ft·lbs. Apparently, they don't want you to do anything to their cars at all." (Unless you had a Nutcracker®.)

"Can you go over how to draw diagrams for these problems? Can you please go over the 'line of action?'" (Yes, and yes.)

"I apologize for turning in such a shameful assignment. I will definitely read the material before class, so I can follow what is going on."

"Does the extra credit from lab count as a part of the total extra credit for the class?"(No, lab points are capped at a 100 points maximum.)

"Would it be possible to do a really good review for the upcoming quiz?" (Let's see how well you can rock the sample quiz from last year.)

"Didn't think it could get any harder. You must be mad smart."

"I think I am going to like this section."

20141021

Physics midterm question: water-filled bucket twirled in a vertical circle

Physics 205A Midterm 1, fall semester 2014
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 5.39

Water is poured into a bucket attached to an ideal string, and is then twirled around in a circle. The speed of the bucket is momentarily constant at the bottom of its circular path. Discuss why the magnitude of the normal force of the bucket on the water is greater than the magnitude of the weight force of Earth on the water. Explain your reasoning by using a free-body diagram, the properties of forces and Newton's laws.

Solution and grading rubric:
  • p:
    Correct. Recognizes that Newton's second law applies to uniform circular motion (constant speed but continuously changing direction) where the (non-zero) net force on the water must point inwards (upwards), thus the upwards normal force of the bucket on the water is greater in magnitude than the downwards weight force of Earth on the water.
  • r:
    Nearly correct, but includes minor math errors. Some attempt at applying Newton's laws to a free-body diagram, but may have a centrifugal or centripetal "m·v/r2" force in addition to the normal and weight forces.
  • t:
    Nearly correct, but approach has conceptual errors, and/or major/compounded math errors. Problematic attempt at applying Newton's laws (N1 or N3) to a free-body diagram (with extraneous or missing forces, or inconsistent with Newton's laws).
  • v:
    Implementation of right ideas, but in an inconsistent, incomplete, or unorganized manner. Effectively only has a substantive attempt at a free-body diagram, or only a substantive attempt at discussing Newton's laws.
  • x:
    Implementation of ideas, but credit given for effort rather than merit. Approach other than that of applying Newton's laws to a free-body diagram.
  • y:
    Irrelevant discussion/effectively blank.
  • z:
    Blank.
Grading distribution:
Sections 70854, 70855, 73320
Exam code: midterm01m0oU
p: 8 students
r: 24 students
t: 28 students
v: 13 students
x: 0 students
y: 0 students
z: 1 student

A sample "p" response (from student 0203):

Another sample "p" response (from student 1828):

A sample "r" response (from student 1914), with an additional centripetal force on the free-body diagram:

A sample "v" response (from student 3474):

Online reading assignment: stellar parameters (NC campus)

Astronomy 210, fall semester 2014
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 presentations on parallax, distance, apparent magnitude, absolute magnitude, Wien's law and the Stefan-Boltzmann law.


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.
"That astronomers use triangulation to calculate the distance of a star. It is nice to see this practical application of trigonometry which, interestingly, can be compared to how surveyors calculate distance as well."

"I found the whole chapter pretty interesting, especially how the color really shows the temperature of the star. This is mostly due to the fact that we usually see blue and white as cool colours, so when it turns out that they're in fact indicators of the hottest suns it seems somewhat counter intuitive. Even though I know blue flames are hotter than red flames, it still seems so odd."

"The Stefan-Boltzamann law, because I was trying to figure out all the concepts (luminosity, temperature, and size) how they all come together to determine different things about the stars."

"How bigger stars aren't necessarily hotter."

"That you can tell which star has the most luminosity based on it's color and size. This is interesting because I didn't know it was so simple as this."

"The charts for determining the luminosity of stars was cool. I didn't think it would be that easy, but it makes sense and is really quick to do!"

"It's cool to know that I'm not crazy or seeing things when I see a star as having a red color."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"How can we measure the distances to stars?"

"The Stefan-Boltzamann law because I feel I still need examples to understand it completely and be able to use it."

"Apparent magnitude and absolute magnitude. It's hard to conceptualize."

"I was confused about what I found to be interesting. That is, why we don't see stars of all colors of the rainbow."

"Light-years and parsecs. I get that they ares a units of measure but why did we choose them? What would be an examples of them?"

Explain how apparent magnitude and the absolute magnitude are defined differently.
"Apparent magnitude is what we see from Earth. Absolute is what the actual brightness is."

Suppose the sun was moved to a distance of 10 parsecs away. As a result, its __________ magnitude would become dimmer.
absolute.  *** [3]
apparent.  ****************** [18]
(Both of the above choices.)  ** [2]
(Neither of the above choices.)  ** [2]
(Unsure/guessing/lost/help!)  **** [4]

Rank the temperatures of these stars (1 = hottest, 4 = coolest; there are no ties).
(Only correct responses shown.)
Hottest: blue main sequence star [70%]
Second hottest: white main sequence star [59%]
Third hottest: yellow main sequence star [83%]
Coolest: red main sequence star [90%]

Rank the temperatures of these stars (1 = hottest, 4 = coolest; there are no ties).
(Only correct responses shown.)
Hottest: blue supergiant [83%]
Second hottest: white dwarf [59%]
Third hottest: yellow supergiant [72%]
Coolest: red dwarf [93%]

Two stars (equally far away) have the same temperature, but one star is dimmer, and the other star is brighter. The __________ star will be larger in size.
dimmer.  *** [3]
brighter.  ************************** [26]
(These stars would be the same size.)  [0]
(Unsure/guessing/lost/help!)  [0]

Two stars (equally far away) have the same brightness, but one star is cooler, and the other star is hotter. The __________ star will be larger in size.
cooler.  ************** [14]
hotter.  ************** [14]
(These stars would be the same size.)  [0]
(Unsure/guessing/lost/help!)  * [1]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"How do they know the temperature of a star?" (By looking at its color.)

"Could we please briefly discuss in class the relationship between a star's color and its temperature?"(Yes.)

"What's up with your hearing aid?" (I had Sudden Sensorineural Hearing Loss (SSHL) a few years ago, when your hearing disappears overnight--and no one really knows what causes it. But FWIW I'm now the world's deafest swing DJ. #fml #strongthanhearingloss)

20141020

Online reading assignment: collisions

Physics 205A, fall semester 2014
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 collisions.


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 understand the different types of collisions. I also understand how to use the conservation law equations."

"Total momentum is a sum total of momenta of objects in a system. Internal interactions do not change total momentum, external interactions might change it. Reading also touches on what a collision is."

"A perfectly inelastic collision occurs when two objects stick together. Inelastic occurs when one object pushes the other away and there's visible damage. Finally, an elastic collision occurs when one object completely pushes another and there is no visible damage."

"I assumed that two objects stuck together wouldn't lose lots of energy, but after reading more about it, they can lose lots of kinetic energy."

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.
"The relative velocity kinetic energy conservation equation just is not clicking for me. A brief explanation of why that equation is what it is would help greatly."

"You lost me at the concept of momentum."

Explain the difference between a (partially) inelastic collision and a perfectly inelastic collision.
"If two cars hit each other and do not stick to each other , but are crushed or bent, then the collision is partially inelastic. If two cars collide and are stuck together, the collision is perfectly inelastic."

"In an inelastic collision both objects bounce off each other and there is visible damage, in a perfectly inelastic collision, however, both objects are stuck together in addition to visible damage."

Explain why drag, friction, and other external forces do not matter during sufficiently "brief" collisions, in order for momentum to be conserved.
"We're limiting it to the initial state just before the collision and the final state just after the collision. The external forces have negligible impulses in the short time span."

"The system needs to be isolated from all external factors, because if it isn't then momentum is not conserved. To put it into context, external forces will always be a factor, but the forces involved within a collision are so large that any external forces can be safely ignored, for they do not alter the final result in a significant way."

For the Nissan Altima and Nissan Rogue crash test, classify the type of collision. (Neglect drag/friction/external forces during this "brief" collision.)
Perfectly inelastic (kinetic energy not conserved).   ** [2]
(Partially) inelastic (kinetic energy not conserved).   **************************************** [40]
Elastic (kinetic energy conserved).   ***** [5]
(Unsure/lost/guessing/help!)   ******** [8]

For the Ford Explorer and Ford Taurus crash test, classify the type of collision. (Neglect drag/friction/external forces during this "brief" collision.)
Perfectly inelastic (kinetic energy not conserved).   ******** [8]
(Partially) inelastic (kinetic energy not conserved).   ****** [6]
Elastic (kinetic energy conserved).   ********************************* [33]
(Unsure/lost/guessing/help!)   ******** [8]

For the train and minivan crash, classify the type of collision. (Neglect drag/friction/external forces during this "brief" collision.)
Perfectly inelastic (kinetic energy not conserved).   ******************************* [31]
(Partially) inelastic (kinetic energy not conserved).   ******* [7]
Elastic (kinetic energy conserved).   ***** [5]
(Unsure/lost/guessing/help!)   ************ [12]

For the bullet burrowing through and back out of the baseball, classify the type of collision. (Neglect drag/friction/external forces during this "brief" collision.)
Perfectly inelastic (kinetic energy not conserved).   *** [3]
(Partially) inelastic (kinetic energy not conserved).   **************************** [28]
Elastic (kinetic energy conserved).   ************ [12]
(Unsure/lost/guessing/help!)   ************ [12]

For the bullet shot out of this gun, classify the type of collision. (Neglect drag/friction/external forces during this "brief" collision.)
Perfectly inelastic (kinetic energy not conserved).   *** [3]
(Partially) inelastic (kinetic energy not conserved).   ****************** [18]
Elastic (kinetic energy conserved).   ******************** [20]
(Unsure/lost/guessing/help!)   ************** [14]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"I am having some trouble understanding elastic, partially inelastic, and perfectly inelastic collisions, and momentum conservation and kinetic energy conservation equations. Would you be able to go over some examples in class please? Could you also go over kinetic energy being conserved or not being conserved?" (Yes. And if time allows, you'll get to solve an example as well.)

"How do you tell the difference between perfectly inelastic and partially inelastic collisions? Is it just the sticking (or not)?" (Yes, for a perfectly inelastic collision, the objects are stuck-together after the collision. It's actually quite common in automobile accidents.)

"What would it be if two objects collided, stuck together, and did not have deformation?" (If there is not visible deformation, then translational kinetic energy was dissipated into other forms, such as sound, heat, etc.)

"Can you go over the last question on the midterm?" (It's discussed on the blog, along with samples of student solutions.)

"Do you celebrate Halloween?" (My people celebrate something called "Madonnaween.")

20141019

Physics midterm problem: Apollo 14 golf swing

Physics 205A Midterm 1, fall semester 2014
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 3.49

"Golf on the Moon (NASA)"
John Gizis (Creative Commons Attribution License 2.5)
http://youtu.be/KZLl3XwlAIE

In February 1971, Apollo 14 astronaut Alan Shepard used a make-shift golf club to hit a golf ball on the moon, and described it as traveling "miles and miles and miles."[*] An online message board[**] discussed reasonable parameters for a golf ball hit by an average golfer:
I am informed by a mathematician, also a keen golfer, that assuming a speed off the club of 37 m/s, which is average, and an elevation of 40°, which is usual for a 6-iron, then a distance [less than one mile] could be expected.
Based on these parameters, determine whether Shepard's "miles and miles and miles" claim or the online "less than one mile" claim is more plausible. The magnitude of the gravitational constant on the moon is gmoon = 1.62 m/s2, and use the approximation 1 mi = 1,600 m. Neglect air resistance. Show your work and explain your reasoning using properties of projectile motion.

[*] Eric M. Jones, "EVA-2 Closeout and the Golf Shots," http://history.nasa.gov/alsj/a14/a14.clsout2.html.
[**] moorouge, "Topic: How far did Alan Shepard's golf ball go?" http://www.collectspace.com/ubb/Forum29/HTML/001181.html.

Solution and grading rubric:
  • p:
    Correct. Finds x- and y-components of the initial velocity vector, then applies projectile motion equations in a methodical manner and determines which claim is more plausible using one of these (or other) approaches:
    • finds Δt for the golf ball to reach the ground, then uses this time to determine the horizontal displacement Δx of the ball, which is less than 1,600 m;
    • finds Δt for the golf ball to theoretically travel a horizontal distance Δx = 1,600 m, then uses this time to determine the vertical displacement Δy of the golf ball, and concludes that since Δy is negative, then the golf ball traveled less than 1,600 m.
  • r:
    Nearly correct, but includes minor math errors. May have the wrong sign on the gravitational acceleration constant, or simple arithmetic errors, but makes a sound argument based on the numerical values resulting from these errors.
  • t:
    Nearly correct, but approach has conceptual errors, and/or major/compounded math errors. At least enough steps are shown that would theoretically result in a complete answer, multiple errors notwithstanding.
  • v:
    Implementation of right ideas, but in an inconsistent, incomplete, or unorganized manner.
  • x:
    Implementation of ideas, but credit given for effort rather than merit.
  • y:
    Irrelevant discussion/effectively blank.
  • z:
    Blank.
Grading distribution:
Sections 70854, 70855, 73320
Exam code: midterm01m0oU
p: 23 students
r: 15 students
t: 8 students
v: 8 students
x: 14 students
y: 5 students
z: 1 student

A sample "p" response (from student 3560), calculating the time for the golf ball to hit the ground, and finding that the horizontal distance traveled during that time would be less than a mile:

Another sample "p" response (from student 0123), calculating the time for the golf ball to travel one mile horizontally, then determining that the golf ball would need to be vertically well below the ground in order to travel that horizontal distance:

Another sample "p" response (from student 1263), calculating the time for the golf ball to reach its highest height, then multiplying that by two to get the total flight time, and rinding that the horizontal distance traveled during that total flight time would be less than a mile:

A sample "y" response (from student 9693), speculating that the golf ball would travel farther than a mile on Earth because of the weaker gravitational constant on the moon.

20141015

Online reading assignment question: confusing Midterm 1 physics topics

Physics 205A, fall semester 2014
Cuesta College, San Luis Obispo, CA

"141015-Phys205AMidterm1confusing---"
https://flic.kr/p/ppgVUm
Originally uploaded by Waifer X

Wordle.net tag cloud for confusing topics covered in Midterm 1, generated by responses from Physics 205A students at Cuesta College, San Luis Obispo, CA (http://www.wordle.net/show/wrdl/8234935/Untitled).

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.

List at least three words describing confusing subjects covered in class (up through this midterm). (Graded for completion.)

[Responses have been edited to consolidate related common subjects.]
impulse, uniformcircularmotion, Newtonslaws
everything
N3 N1
friction, projectilemotion, freefall
work, impulse, N3
uniformcircularmotion, Newtonslaws, friction
Newtonslaws, N1 N3
uniformcircularmotion
freebodydiagrams
Icannotyetsay
uniformcircularmotion
heartbreak, shatter, confusion
projectilemotion, vectorcomponents, tension, N3
projectilemotion, kinematicequations
freefall, projectilemotion, kinematicgraphs
hard, confusing, tedious
forces
explainreasoning
velocity, acceleration, magnituce
tension, acceleration, N3, centripetalforce
uniformcircularmotion, freebodydiagrams, magnitudes,
Newtonslaws, acceleration, tension
uniformcircularmotion, freebodydiagrams
averageangularacceleration, translationalkineticenergy, impulse
everything, flipclass
vectors, drag, Newtonslaws
uniformcircularmotion, projectilemotion, Newtonslaws
uniformcircularmotion, projectilemotion
centrifugalforce, netforce, vectors, friction
N3, tension, pulleys
uniformcircularmotion, N3
kinematicgraphs, freebodydiagrams, vectorcomponents
Describe your most confusing subject, and briefly explain why this subject interested you. (Graded for completion.)

The following are all of the student responses to this question, verbatim and unedited.
"impulse, circular motion, and newtons laws is confusing to me because i havent fully been able to grasp the concept of how it relates to the real world."

"Every chapter, because I am a logical thinker and it is very confusing to me when I cannot use it in the problems."

"Uniform circular motion, I guess it is still not intuitive why a force is directed inwards towards the center of the circle, but you feel like something is pulling you outward (such as making a sharp turn in a car)"

"Probably Newton's third Law. I like POF OST ITO, but it's hard for me to relate the two diagrams to each other."

"Impulse has been the most confusing concept for me. There is just a lot to grasp when we account for the time which a force is applied and how that will affect the velocity change and work being done on another object,"

"Friction forces because I get mixed up on static friction very easily"

"Circular motion. I feel like we didn't cover that material well enough."

"Uniform circular motion is the most confusing to me. Not really sure why, it just doesn't seem to click like other subjects."

"Im very confused by free body diagrams."

"I cannot yet say"

"The way normal forces and weight forces interact in some situations was difficult for me to understand."

"Static friction will be my most challenging subject, but I will be prepared. I find it challenging finding all the forces acting upon an object. But none of this will hold me back."

"I had the most difficult time with projectile motion (especially the diagonally launched projectile motion) because it is hard for me to figure out what each given is from a written problem. Each circumstance is different and just when I think I understand it I miss one little "given" and mess up a whole problem."

"the five equations because I'm not of the most statistically-based mindset."

"the equations that I had to do with projectile motion were probably the most confusing because there were so many equations to pick from."

"Applying forces, Newtons laws, and friction in one problem. It is doable but there are so many variables needed or need to figure out that it can get a bit confusing sometimes."

"The forces were kindof confusing, especially when dealing with the ideal pulleys...."

"I think it is most confusing when answering a problem about Newtons laws, and other motions, using the correct terms to justify the answer, even if the answer is correct."

"The cointoss across the Pitomac river."

"Forces dealing with pullies and acceleration were confusing to me because it is sometimes difficult figuring out the direction of net force."

"Sometimes I cannot follow how you get numbers when using a free body diagram and I'm worried that it will be a big part of the midterm."

"I found Newton's Laws confusing because they all seem very similar to me and I have trouble in telling the differences."

"horizontal free body diagrams involving the cylinders, its difficult for me because its hard for me to visually picture it."

"Impulse seemed intuitive when I was first introduced to it. But the example of the baseball and Bay really confused me because it seems like even if you were in contact with the ball for a longer period of time they the ball would already start to fall and the lesser speed wouldn't make as much of an impact."

"Sliding and falling connected boxes. Would have never done the correct procedure to solve this problem."

"Perhaps the most confusing thing is uniform circular motion. Is it actually possible to tell if a circle is uniform?? Kind of unrelated. Sorry."

"newtons laws are probably the most confusing. I get lost in which law is supposed to be applied."

"Uniform circular motion, I'm still not sure why normal force is decreased when velocity increased. Actually as I was typing this I think I figured it out. Since normal force is opposite of weight force, the faster the velocity the less normal force is going to push back."

"That double box problem asking to explain why the friction force of the top box on the bottom box is directed right. I understand that because of newtons 3 law there is an opposite and equal force directed right but that still make no sense in my brain."

"I found Newton's third law confusing. I found it difficult to discern what objects are interaction partners or not."

"circular motion! :( I don't know why... it is kind of mind twisting..."

"I get messed up sometimes when I try to set up diagrams to represent angles and forces. I'm very visual and I like to use visuals, but often times I switch things up and don't use common sense when it should be used."

Online reading assignment question: interesting Midterm 1 physics topics

Physics 205A, fall semester 2014
Cuesta College, San Luis Obispo, CA

"141015-Phys205AMidterm1interesting---"
https://flic.kr/p/oJPSBd
Originally uploaded by Waifer X

Wordle.net tag cloud for interesting topics covered in Midterm 1, generated by responses from Physics 205A students at Cuesta College, San Luis Obispo, CA (http://www.wordle.net/show/wrdl/8234934/Untitled).

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.

List at least three words describing interesting subjects covered in class (up through this midterm). (Graded for completion.)

[Responses have been edited to consolidate related common subjects.]
kinematics, horizontalmotion, freefall, fictitiousforces
forces, N1 N2
projectilemotion, Newtonslaws
friction, projectilemotion, freefall
uniformcircularmotion, friction, freefall
projectilemotion, uniformcircularmotion, Newtonslaws
projectilemotion, freefall, N3
projectilemotion, freebodydiagrams
Newtonslaws, freefall, displacement
friction, freefall, motion
friction, tension, N1
Newtonslaws, friction, projectilemotion
uniformcircularmotion, drag, friction
physics, motion, wow
friction, Newtonslaws
fun, understandable, repetitive
projectilemotion
averagespeed instantaneousspeed, averagevelocity, instantaneousvelocity
friction, Newtonslaws, dimensionalanalysis
Newtonslaws, centripetalforce, projectilemotion
projectilemotion, freebodydiagram, Newtonslaws
displacement, distancetraveled, velocity
uniformcircularmotion
projectilemotion, uniformcircularmotion, averageangularvelocity
projectilemotion, normalforce, vectorcomponents
projectilemotion, tension, friction
Newtonslaws, projectilemotion, kinematicgraphs
velocity, speed, friction
Newtonslaws, centrifugalforce, friction
velocity, projectilemotion, forces
friction, projectilemotion, freefall
friction, freefall
friction, velocity, energy
Describe your most interesting subject, and briefly explain why this subject interested you. (Graded for completion.)

The following are all of the student responses to this question, verbatim and unedited.
"kinematics, horizontal and vertical motion, and fictional forces is interesting because friction can affect motion and motion can be solved and predicted by kinematics. In a sense they all relate to eachother"

"Newton's Law, very hard topic but interesting everything works and I many cases logical thinking doesn't help. Bungee jumping, I do bungee jump and skydive so this was interesting to see the results from physics perspective."

"Projectile motion, because there are formulas I can use to find relevant pieces of information."

"Probably terminal velocity. It's just an interesting subject to me, I like the thought of it. That there is only a certain speed that an object can fall and at that moment it is going fast, but not accelerating. I like that subject."

"Normal forces were pretty interesting to me. It never occured to me that when you apply a force on an object, and the object's velocity doesn't change as a result, that object is "pushing back" against the force, even though a typical person would think the only thing pushing is the force itself."

"Newtons laws because it's three very simple statements that can apply to so many things in many different ways."

"Trajectory. Its very hands on. I like that."

"To me, Newton's laws and free body diagrams were the most interesting. It is really cool to be able to break down the specific forces in an action and see how they react with each other."

"I cannot yet say, but to guess ahead of time, high-speed car propulsion w/ ramp."

"I like how Friction works and I understand the differences between Static and Kinetic"

"Finding the means for acceleration and velocity in objects."

"The most interesting for me to learn was uniform circular motion because I have seen so many rollover accidents before and have been involved in one. Learning about some of the physics behind it made me to think about the design of these cars and how different factors can cause vehicles to flip. Also it made me understand just how beneficial it could be to understand physics to better design products in general. It can literally save lives!! (Oh and it can make life more fun because we can design awesome circular rides that are safe!!)"

"Newton's Laws. Because they're cool."

"Friction was the most interesting to me because it made the most sense and i never though of friction pullinf in the opposite direction of the object that is against it."

"I like the subject of projectile motion. What we have learned so far seems simple like an object being thrown at an angle and figuring out stuff."

"The friction part that we studied is very interesting. Now while at work I find myself constantly thinking about the friction required. For example, the other day I was parking a dump truck on a job and its parking brake is a drum, and you pull the lever up and it pushes the pads out against the drum, which is connected to the driveline which stops it from moving...unless you are on a steeper hill. The numbers starting running through my head about how much it would take to stop the truck weighing 16+ thousand pounds....very interesting...."

"The most interesting subject covered was the difference between speed and velocity, I found it interesting that the path travelled made a difference in the velocity."

"The coin tossed across the Pitomac River as it sortof relates to the same relatvie problem of the stunt car not making it over the river. Especially when it came to the point landing below y-axis."

"Projectile motion, because it is interesting to me that the x velocity of an object moving through air (with no air resistance) does not have an effect on the y velocity or time in air."

"I liked projectile motion because it can be used in so many different situations and sometimes I think its a lot easier to just plug and chug and equation."

"Displacement because I found it interesting that can be the same as distance traveled and that it can also be different."

"projectile motion, because i understand it."

"Finding the change in acceleration. I enjoy being able to graph the values I find it makes visualization easier."

"Washington's Throw, it is easier to gauge if any outcome is outrageous by comparing to previous knowledge."

"Projectile motion is probably the most interesting because I wonder how it is possible this stuff was ever discovered!"

"projectile motion, it seems the most applicable to everyday things."

"The difference in normal force with banked and unbanked roadways."

"I think it's interesting how the max static force is higher then the max kinetic force."

"Projectile motion is interesting to me"

"I found predicting quantities of a trajectory very interesting and applicable to many real life scenarios."

"Kinetic and static friction. It is interesting that a force (static friction) has a range and that the kinetic friction is smaller than static. I don't know why, but I find interesting the reactions between different surfaces and how they differ depending on the kind of surface, but not the area of that surface."

"Force was the most interesting so far because it is applicable. I can accurately make an estimate on how much heavier a ball would be if I dropped it off of my balcony and into my friends hands."

Online reading assignment question: helpful/unhelpful Midterm 1 physics study tips

Physics 205A, fall semester 2014
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.

Describe something notable that either helped or did not help with studying for this midterm. Selected comments may be discussed in class. (Graded for completion.)

The following are all of the student responses to this question, verbatim and unedited.
"a brief definition of each term and when to use it"

"similar questions to the midterm questions"

"For future reference, some kind of study guide involving various relationships such as F = Ma, etc"

"I think your examples from previous tests with worked out answers will help me study for this midterm."

"Don't go on a trip to Vegas during your flex days and not study like I just did. The longer you stay away from your studying, the harder it will be to review everything. (By, the way, I got a day pass rode the roller coaster at the New York-New York hotel a total of 18 times one night. Several times I kept thinking about gravitational potential energy and how I should be studying physics instead of riding this thing over and over.)"

"Doing practice oroblems is the only way I feel prepared."

"More sample problems worked out!!!"

"The fact that very few houses in this area have air conditioning will not help me study for this midterm."

"Although there was ample time to study, due to the flex days, I would have preferred to take the exam before a five-day weekend, prone to vacation, partying, and such..."

"The flipped class concept is difficult and confusing for me."

"Get away from distractions and lose your self into the world of physics."

"Reading/studying the blogs, posts, ect. on the waiferx site FIRST and then studying out of the book has helped me. I focused more on the book before recently and I think it has helped me to use the website first then the book. To start with the book made physics way too confusing for someone like me with absolutely NO physics or science background (only math)."

"Group studying"

"Don't really know what this question is asking from me but I need to study a ton for this midterm"

"Writing down key point of each subject helps to be more organized. Every time I come across something important I write it down so I don't get confused about the other less important stuff in the book."

"The problems that were posted to help us study were very helpful, i just hope the problems on the midterm will be similar to these problems!!!!!"

"Something that would help, would having more example problems that I could practice similar to the ones on the exam because the book does not have a good sample problem set."

"I just need to review all the reading and notes as well as some example problems."

"I have studied the review many times, and I have gone over the definitions as well to make sure I have a good grasp on all of the material."

"procrastinating."

"One of the things that helped me was to go over the summary of each section in the book then if there was a term I didn't understand I would write it down for later."

"Feverant outside help"

"I will be reading the text, drawing flamboyant diagrams, and trying out practice problems. I hope these methods will be effective."

"Just going over class notes and mostly example problems that we did in class."

"Going through the definitions of all the notable terms, especially for the short answer topics."

"I want more examples with explainations."

"A specific study guide would help"

"Some more cool YouTube videos that illustrate the concepts in class, would make it easier to learn."

"Other textbooks, for some reason I don't like the one we are using."

"Review on a topic that was missed most by previous classes."

Online reading assignment: Kirchhoff's laws (SLO campus)

Astronomy 210, fall semester 2014
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 presentations on Kirchhoff'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.
"That blue light is the warmest light. I thought it would have been yellow or red."

"I found the 'neeeeoooooowwww' effect interesting because I now know why sounds stretch as they move past."

"I think the part where the sound is being stretched or squished is interesting. I didn't know movement had an effect on the pitches of sound. Which kind of made me think how ambulances sound one they pass you, which is like a farther more 'stretched' out sound."

"I found it interesting that how spectra related to barcodes."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"I'm confused as to what the dopler effect is. Is it moving sound?"

"Need more explanation on how to determine the different types of light spectra."

"The different spectra pictures were kind of confusing determining which kind they were. Im not sure if I'm right or wrong with them so I stopped guessing."

"Blueshift versus redshift."

I believe Pluto should be a planet.
Strongly disagree.  ***** [5]
Disagree.  ******* [7]
Neutral.  *********** [11]
Agree.  ***** [5]
Strongly Agree.  ** [2]

Briefly explain your answer to the previous question (whether Pluto should be a planet).
"The nostalgia inside of me wants Pluto to still be a planet but the scientist tells me thats wrong. Pluto does not dominate its orbit therefore does not reach one of the requirements of being a planet."

"I feel like once you say a planet is a planet you should not be able to change your mind."

"It is not technically a planet, if we let Pluto be a planet than we would have to let many other dwarf planets be considered planets."

"Whether Pluto is a planet or not does not affect my daily life."

"People should just realize that views change and Pluto doesn't care. If it doesn't dominate its orbit, it must be a dwarf planet."

Match the spectrum type with their appearance.
(Only correct responses shown.)
Rainbow containing all colors: continuous [90%]
Rainbow with thin black lines: absorption [80%]
Colored lines on a black background: emission [83%]
Given off by hot, dense object: continuous [75%]
Given off by hot, diffuse gas atoms: emission [82%]
Passing through cool, diffuse gas atoms: [82%]

Hot, molten metal produces a __________ spectrum, which appears as a:
continuous; rainbow.  ** [2]
emission; series of bright lines on a dark background.  *** [3]
absorption; series of dark lines on a rainbow background.  **** [4]
(Unsure/guessing/lost/help!)  [0]

The sun produces a __________ spectrum, which appears as a:
continuous; rainbow.  * [1]
emission; series of bright lines on a dark background.  **** [4]
absorption; series of dark lines on a rainbow background.  *** [3]
(Unsure/guessing/lost/help!)  * [1]

The lights atop the Fremont Theater in San Luis Obispo, CA, produces a __________ spectrum, which appears as a:
continuous; rainbow.  **** [4]
emission; series of bright lines on a dark background.  ***** [5]
absorption; series of dark lines on a rainbow background.  [0]
(Unsure/guessing/lost/help!)  [0]

Your instructor produces a __________ spectrum, which appears as a:
continuous; rainbow.  *** [3]
emission; series of bright lines on a dark background.  *** [3]
absorption; series of dark lines on a rainbow background.  ** [2]
(Unsure/guessing/lost/help!)  * [1]

The balrog from The Lord Of The Rings: The Fellowship Of The Ring produces a __________ spectrum, which appears as a:
continuous; rainbow.  * [1]
emission; series of bright lines on a dark background.  ****** [6]
absorption; series of dark lines on a rainbow background.  ** [2]
(Unsure/guessing/lost/help!)  [0]

Suppose you are standing on the sidewalk as a car, with its horn continuously on, passes by (video link). The loudness of the car horn:
starts loud, then gets quieter.  ******* [7]
starts quiet, then gets louder.  [0]
starts quiet, gets louder, then goes back down to quiet.  ********************** [22]
starts loud, gets quieter, then goes back up to loud.   * [1]
(Unsure/guessing/lost/help!)  [0]

Suppose you are standing on the sidewalk as a car, with its horn continuously on, passes by (video link, same as above). The pitch (high note/low note) of the car horn:
starts high, then drops lower.  **************** [16]
starts low, then goes higher.  *** [3]
starts low, goes higher, then drops back down to low.  ******** [8]
starts high, goes lower, then goes back up to high.   *** [3]
(Unsure/guessing/lost/help!)  [0]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Will people get over the fact that Pluto is no longer a planet?" (They should make like Elsa and 'Let It Go.')

"I thought using that Lord of the Rings movie clip was AMAZING!!!! Let's discuss this more in class please!!!!!!!:):):):)" (Can't hold it back anymore--let it go, let it go, turn away and slam the door!)