20140918

Astronomy quiz question: Saturn in retrograde

Astronomy 210 Quiz 2, fall semester 2014
Cuesta College, San Luis Obispo, CA

The diagram at right shows Saturn's position in the constellation Libra as seen by an observer in San Luis Obispo, CA. Saturn is currently undergoing retrograde motion. The following night Saturn will be __________ this position in the constellation Libra.
(A) slightly to the left of.
(B) slightly to the right of.
(C) exactly at.
(D) (Not visible at all the following night.)

Correct answer (highlight to unhide): (B)

When Saturn is undergoing prograde motion, it will move from west to east (in this perspective, right to left, as shown in blue) with respect to the background stars over consecutive nights. When Saturn is undergoing retrograde motion, it will move from east to west (in this perspective, left to right, as shown in red) with respect to the background stars over consecutive nights.

Section 70158
Exam code: quiz02n3w7
(A) : 15 students
(B) : 24 students
(C) : 3 students
(D) : 0 students

Success level: 59% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.74

Section 70160
Exam code: quiz02k3pL
(A) : 9 students
(B) : 20 students
(C) : 5 students
(D) : 0 students

Success level: 61% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.56

Astronomy quiz archive: eclipses/history of astronomy

Astronomy 210 Quiz 2, fall semester 2014
Cuesta College, San Luis Obispo, CA

Section 71058, version 1
Exam code: quiz02n3w7


Section 30674
0- 8.0 :   ** [low = 4.5]
8.5-16.0 :   ******
16.5-24.0 :   ************
24.5-32.0 :   ********* [mean = 25.5 +/- 8.7]
32.5-40.0 :   ************* [high = 40.0]


Section 71060, version 1
Exam code: quiz02k3pL


Section 30676
0- 8.0 :   ** [low = 8.0]
8.5-16.0 :  
16.5-24.0 :   ***********
24.5-32.0 :   ************ [mean = 26.5 +/- 7.8]
32.5-40.0 :   ********* [high = 40.0]

20140917

Online reading assignment: atmosphere problems, Earth, the moon, Mercury (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 problems caused by the atmosphere for telescope observing, Earth, and the impacted worlds: the moon, and Mercury.


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 found it interesting that light from towns blocks us from seeing all the stars, I've noticed this when I go out camping but I never knew why I would see more stars out camping than in a city or anywhere with a lot of man-made light. Made me want to move."

"How the atmosphere can distort the views of space through our eyes and telescopes."

"That we have placed telescopes so high up (including mountain summits and space) in order to bypass atmospheric turbulence. It never occurred to me that seeing into space could be so obstructed by something like that."

"How volcanic activity emits carbon dioxide, and how our oceans not only help collect the water vapor from volcanic activity, but also absorbs carbon dioxide."

"I did not realize Mercury and the moon's appearance are so similar."

"I like the example of how carbon dioxide dissolved in the water because it is highly soluble in water--which explains the easy manufacture of carbonated beverages."

"I liked the turkey-cornish hen analogy. It made it easy to understand why bigger planets are hotter."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"Active optics versus adaptive optics. It makes it less distorted but smaller? How exactly does adaptive optics remove 'twinkling' movements in images of stars?"

"I'm wondering where the funding comes from for all of these satellites and spacecraft. This is personally confusing for me because I am so broke."

"I don't really understand why we use radio telescopes. I'm not sure what the benefit is of knowing that information."

Stars to appear to "twinkle" in the night sky because of:
"Distortions caused by telescopes."

"Much like looking up at the sky underwater the sky looks distorted from the motion of the water, making it appear differently. it is in the same sense that when looking at the sky at night the air distorts the sky making the stars look like they are twinkling."

"Atmospheric turbulence."

A large modern optical telescope in outer space would have images with better __________ than a comparable ground-based telescope.
brightness.   ** [2]
resolution.   **************** [16]
magnification.   *** [3]
(None of the above choices.)   * [1]
(Two of the above choices.)   ***** [5]
(All of the above choices.)   *********** [11]
(Unsure/guessing/lost/help!)   [0]

Identify how carbon dioxide enters and how it is taken out of Earth's atmosphere. (Only correct responses shown.)
Enters atmosphere from: volcanoes [61%]
Taken out of atmosphere by: oceans [53%]

Identify the oldest (longest ago) to the youngest (most recent) features on the moon. (Only correct responses shown.)
Craters partially filled in with flat lava plains: oldest (formed longest ago) [32%]
Flat lava plains: middle [55%]
Craters on top of flat lava plains: youngest (formed most recently) [45%]

Identify the oldest (longest ago) to the youngest (most recent) features on Mercury. (Only correct responses shown.)
Large crater basins: oldest (formed longest ago) [53%]
Lava-filled lowlands: middle [47%]
Long curving ridges: youngest (formed most recently) [68%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"How do you differentiate between a star and a planet?" (To the naked eye, stars twinkle, but planets do not twinkle (and are also found in slightly different positions in the sky night after night).)

"If stars don't really twinkle, then why is there still movement shown in the adaptive optics *.GIF? (Removing twinkling using adaptive optics is not completely perfect, but only needs to be as good as the resolving power of the telescope. Any more correction is not going to matter.)

"What are the oldest parts of the moon and Mercury?" (We'll go over this in class, along with more details on adaptive optics.)

"I like this class. I've been studying a lot more for the second quiz since I did so poorly on the first one. I feel pretty confident in my comprehension of the material, but I did the first time too, so..." (Good luck, and try your best!)

Online reading assignment: Newton's third law

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 Newton's third law.


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.
"When two objects interact they both exert a force on the other."

"I have a great understanding of Newton's first and second laws using the motion flow chart. It makes the questions much easier."

"Whereas Newton's first and second laws have to do with motion and net force, Newton's third law has to do with symmetry."

"Interaction pairs are formed when two objects are in contact with one another and exert equal, yet opposite, forces on each other. Not all equal/opposite forces are an interaction pair, as there must be two objects interacting with each other."

"Newton's third law says that interaction partners always have the same magnitude and are opposite in direction. Also, Newton's third law isn't involved every time two forces happen to be equal and opposite."

"One of the differences between Newton's first law and Newton's third law is that Newton's third law requires the same type of forces (weight-weight, etc.), whereas Newton's first law can involve two different types of forces."

"I understand the three-part checklist to determine if Newton's third law applies. If even one check fails, Newton's third law does not apply."

"One can describe the same force in two different ways because of Newton's third law."

"I understand that I need to do this reading!"

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 am confused by what it is talking about in 'a system.' I do not understand what it is distinguishing between an internal and external system."

"Newton's third law--specifically by in an interaction between two objects, whether/how each object's force is equal in magnitude to the other."

"I don't know how to distinguish between when Newton's first law applies and when Newton's third law applies. Also I wasn't 100% sure of the questions at the end of this form."

Consider two categories of motion: (1) Velocity that is constant and unchanging. (2) Velocity that is changing. Discuss whether or not there would be a third category of motion not already covered under these two categories.
"Something with no velocity?"

"How about velocity that is neither constant nor changing?"

"I am completely lost on this question and need to go over it in class."

"No, because either the acceleration is zero, or the acceleration is non-zero, which covers both categories."

"There would not be a third category--either velocity is constant or velocity is changing--it's a binary concept."

An "interaction pair" (or "interaction partners") refers to a pair of:
objects.   **** [4]
forces.   ************************************ [36]
(Both of the above choices.)   ***************** [17]
(Unsure/guessing/lost/help!)   [0]


According to Newton's first law, the normal force of the person's head on the stack of books is equal in magnitude and opposite in direction to the:
normal force of the stack of books on the person's head.   *************** [15]
weight force of Earth on the stack of books.   ************************ [24]
(Both of the above choices.)   ********* [9]
(Neither of the above choices.)   ****** [6]
(Unsure/guessing/lost/help!)   *** [3]


According to Newton's third law, the normal force of the person's head on the stack of books is equal in magnitude and opposite in direction to the:
normal force of the stack of books on the person's head.   *************************** [27]
weight force of Earth on the stack of books.   **************** [16]
(Both of the above choices.)   ****** [6]
(Neither of the above choices.)   **** [4]
(Unsure/guessing/lost/help!)   **** [4]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"If the net force is not zero then is the velocity not constant anymore? Do we use Newton's second law of motion? (Yes, and yes!)

"In any case involving two (interacting) objects, are there always at least two of Newton's laws in effect? For example, Newton's first law and third law, or Newton's second law and third law?" (Yes--either the first law or the second law in terms of the motion of the objects (constant or changing), and the third law in terms of how the objects interact with each other.)

"Are internal forces meant to be inside or something? Or is it more like forces within a set of objects, and we call them a 'system' because we want to look at the forces that they are contributing as a whole?" (Yes...and yes.)

"I am not sure how to differentiate between Newton's first law and Newton's third law for forces acting on/between the stack of books and the person's head. I also don't really understand the homework questions." (I'm going to allocate time to carefully go over these at the start of the next class.)

"It would be more helpful to have class discussions instead of working in groups and then going over the correct answers." (Sure, as long as you keep asking good questions for me to answer, either here on the reading assignments, or during class. That said, committing your answers in writing and then having a high-level discussion verifying how you got those answers with your peers is an important part of the learning process emphasized in this class.)

20140916

Physics quiz question: direction of motion on vx(t) graph

Physics 205A Quiz 2, fall semester 2014
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 2.11

A vx(t) graph of an object 
traveling along a straight line is shown at right. The object starts at x = 0 at t = 0. The object is traveling in the +x direction at:
(A) t = 1 s.
(B) t = 3 s.
(C) t = 5 s.
(D) (More than one of the above choices.)

Correct answer (highlight to unhide): (C)

From 0 s < t < 4.5 s, the object has negative vx values, and thus is moving in the –x direction at t = 1 s and t = 3 s. From 4.5 s < t < 6 s, the object has positive vx values, and thus is moving in the +x direction at t = 5 s.

Sections 70854, 70855, 73320
Exam code: quiz02T1o9
(A) : 3 students
(B) : 1 students
(C) : 35 students
(D) : 31 students

Success level: 50%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.82

Physics quiz question: free fall, initial downwards velocity

Physics 205A Quiz 2, fall semester 2014
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 2.47

A pumpkin was dropped in 2007 from the top of Tioga Hall as part of a long-running Halloween tradition at the University of California, San Diego.[*] The pumpkin fell for approximately 2.3 s before hitting the ground 41.1 m below.[**][***] Neglect air resistance. Choose up to be the +y direction.

"UCSD JMC Pumpkin Drop 2007"
0racleman
http://youtu.be/2hMCbYwlm3c

The pumpkin was released with an initial (downwards) velocity of:
(A) –29 m/s.
(B) –28.4 m/s.
(C) –18 m/s.
(D) –6.6 m/s.

[*] Pat Jacoby, "Media Advisory: Annual UCSD Monster Pumpkin Drop," October 29, 2007, http://ucsdnews.ucsd.edu/archive/newsrel/events/10-07MonsterPumpkinDropPJ-L.asp.
[**] 30 frames at 13 fps, http://www.youtube.com/watch?v=2hMCbYwlm3c.
[***] "Height (estimated): 134.84 ft," http://www.emporis.com/building/tiogahall-sandiego-ca-usa.

Correct answer (highlight to unhide): (D)

The following quantities are given (or assumed to be known):

t = 2.3 s,
y = -41.1 m,
ay = -9.80 m/s2.

So in the equations for constant acceleration motion in the vertical direction, the following quantities are unknown, or are to be explicitly solved for:

vfy - viy = ay·t,

y = (1/2)·(vfy + viyt,

y = viy·t + (1/2)·ay·(t)2,

vfy2 - viy2 = 2·ay·y.

With the unknown quantity viy to be solved for appearing in the third equation, with all other quantities given (or assumed to be known), then (with significant figures underlined, but not rounded until the final numerical result is given):

viy·∆t = ∆y - (1/2)·ay·(∆t)2,

viy = (∆y - (1/2)·ay·(∆t)2)/∆t,

viy = (-41.1 m - (1/2)·(-9.80 m/s2)·(2.3 s)2)/(2.3 s),

viy = (-41.1 m + 25.921 m)/(2.3 s),

viy = (-15.179 m)/(2.3 s) = -6.5995652174 m/s,

or to two significant figures, -6.6 m/s.

Response (A) is (∆y/∆t + (1/2)·ay·(∆t)2)/(∆t); response (B) is sqrt(2·∆y·ay); response (C) is ∆y/∆t.

Sections 70854, 70855, 73320
Exam code: quiz02T1o9
(A) : 18 students
(B) : 7 students
(C) : 18 students
(D) : 27 students

Success level: 39%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.80

Online reading assignment: atmosphere problems, Earth, the moon, Mercury (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 problems caused by the atmosphere for telescope observing, Earth, and the impacted worlds: the moon, and Mercury.


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 did not know that most of our carbon dioxide came from volcanoes, so I thought that was pretty interesting."

"I didn't know that the ocean absorbed most of the carbon dioxide."

"Both interesting and confusing is that the moon was speculated to be formed originally from a fragment of a planet that collided with the Earth."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"The amount of elements and processes that created Earth were somewhat unorganized in this textbook and without prior knowledge I would have been overwhelmed and confused."

"I wasn't confused."

"How to figure out the oldest and youngest features of Mercury or the moon, because you have to take into consideration a lot factors that could have caused each feature and what would happen as a result of this event or what would follow."

"that the moon was created by a fragment of a planet. How is that even possible that a fragment could form into a sphere?"

Stars to appear to "twinkle" in the night sky because of:
"Stars look like they are twinkling because we are viewing them through the turbulence of the atmosphere."

"The air of our atmosphere is turbulent. There is constant disturbance in the traveling light due to that, especially if the light has to travel through a lot of the atmosphere, as it does if the stars are only a few degrees from the horizon."

A large modern optical telescope in outer space would have images with better __________ than a comparable ground-based telescope.
brightness. *** [3]
resolution. ****** [6]
magnification. ** [2]
(None of the above choices.) * [1]
(Two of the above choices.) ****** [6]
(All of the above choices.) ******* [7]
(Unsure/guessing/lost/help!) ** [2]

Identify how carbon dioxide enters and how it is taken out of Earth's atmosphere. (Only correct responses shown.)
Enters atmosphere from: volcanoes [67%]
Taken out of atmosphere by: oceans [59%]

Identify the oldest (longest ago) to the youngest (most recent) features on the moon. (Only correct responses shown.)
Craters partially filled in with flat lava plains: oldest (formed longest ago) [48%]
Flat lava plains: middle [44%]
Craters on top of flat lava plains: youngest (formed most recently) [67%]

Identify the oldest (longest ago) to the youngest (most recent) features on Mercury. (Only correct responses shown.)
Large crater basins: oldest (formed longest ago) [59%]
Lava-filled lowlands: middle [41%]
Long curving ridges: youngest (formed most recently) [56%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"We're getting a new space telescope in 2018? Dude, yes I am so pumped for better pictures of the universe. Current images of nebulae and galaxies are rad as all get out, but will this telescope be better. Very cool."

"What is your favorite pastime? How did you meet Mrs. P-dog?" (Swing dancing, especially when I get to DJ at the Madonna Inn on Monday nights. Which is how I first met Mrs. P-dog.)

20140915

Physics quiz archive: kinematics, free fall

Physics 205A Quiz 2, fall semester 2014
Cuesta College, San Luis Obispo, CA
Sections 70854, 70855, 73320, version 1
Exam code: quiz02T1o9



Sections 70854, 70855, 73320 results
0- 6 :   ** [low = 3]
7-12 :   **********
13-18 :   ********************
19-24 :   *********************** [mean = 19.8 +/- 6.3]
25-30 :   *************** [high = 30]

Online reading assignment: forces and motion

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 forces and 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.
"I understand that Newton's first law applies when the net force acting on an object is zero, and the object has a constant speed and a constant direction. I also understand that Newton's second law of motion states that an object's acceleration is proportional to the net force acting on it and inversely proportional to its mass."

"Newton has three laws, but only two of them classify motion. The first law applies to an object that has a constant speed and constant direction or when a net force that equals zero. The second law applies to an object that does not have constant speed or constant direction or when a net force does not equal zero."

"Newton's first law works with objects traveling at a constant speed, in a constant direction. Or it does not move at all. Then the second law states that an object will not move unless it has some force to make it move."

"The difference between Newton's first and second law. I also know when to use which law."

"Newton's first law, how no force is required to keep an object in motion if there are no forces opposing its motion."

"The motion flowchart, in that if an object's speed and direction are constant we can apply Newton's first law. If either of the two aren't constant, we use Newton's second law."

"A change in movement for an object only happens if a force is applied. This includes gravity or air resistance. Inertia refers to an object's tendency to resist movement. The amount of mass and the inertia of it are closely related. The smaller the mass the less inertia it will have."

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 found Newton's laws to be a bit confusing and how to apply them to situations. Like the zero and non-zero net forces."

"The relationship that constant speed and constant direction have with the first and second law. Having trouble getting the differences between the laws."

Identify whether a zero or non-zero net force corresponds to Newton's first law or Newton's second law. (Only correct responses shown.)
Zero net force (ΣF = 0): Newton's first law ("N1") [88%]
Non-zero net force (ΣF ≠ 0): Newton's second law ("N2") [86%]


For the rocket sled, Newton's __________ law applies to the motion of this object, and the forces acting on the object add up to a __________ net force.
first; zero.  ************* [13]
second; non-zero.  ****************************************** [42]
(Unsure/guessing/lost/help!)  ** [2]


While the F-35B is descending (before it touches the ground), Newton's __________ law applies to the motion of this object, and the forces acting on the object add up to a __________ net force.
first; zero.  ****************************** [30]
second; non-zero.  ***************** [17]
(Unsure/guessing/lost/help!)  ********** [10]


For this car with a steady speedometer reading (and assuming the shaking is due to the person holding camera, and not from moving the car itself), Newton's __________ law applies to the motion of this object, and the forces acting on the object add up to a __________ net force.
first; zero.  ****************************************** [42]
second; non-zero.  ********** [10]
(Unsure/guessing/lost/help!)  ***** [5]


For a person in the swinging chair ride moving along a circular trajectory at a constant speed, Newton's __________ law applies to the motion of this object, and the forces acting on the object add up to a __________ net force.
first; zero.  ************************** [26]
second; non-zero.  *************************** [27]
(Unsure/guessing/lost/help!)  **** [4]


For this car with a zero speedometer reading, Newton's __________ law applies to the motion of this object, and the forces acting on the object add up to a __________ net force.
first; zero.  ****************************************** [42]
second; non-zero.  ********** [10]
(Unsure/guessing/lost/help!)  ***** [5]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"These motion examples are confusing because I don't fully understand how to apply Newton's Laws to them. We should quickly discuss these examples in the next class if there is time." (Yes. We totally should.)

"What questions can one ask oneself to determine whether it is Newton's first law or second law? (What questions? These questions. And these other questions.)

"Are the first two laws different in that one has no acceleration and the other doesn't, or is there more to it?" (Awesome--that's exactly how Newton's first two laws work.)

20140913

Astronomy current events question: traces of the oldest stars

Astronomy 210L, fall semester 2014
Cuesta College, San Luis Obispo, CA

Students are assigned to read online articles on current astronomy events, and take a short current events quiz during the first 10 minutes of lab. (This motivates students to show up promptly to lab, as the time cut-off for the quiz is strictly enforced!)
Ashley P. Taylor, "Found: Traces of Some of the Oldest Stars in the Universe," August 21, 2014
http://www.popularmechanics.com/science/space/deep/traces-of-some-of-the-oldest-stars-in-the-universe-17119568
Evidence of the oldest stars in the universe were obtained from observations from the Japanese Subaru telescope on Mauna Kea of a star:
(A) not part of any galaxy.
(B) exploding at an extremely slow rate.
(C) seen through distorted space-time.
(D) formed from their supernova fragments.
(E) being ejected from a wormhole.

Correct answer: (D)

Student responses
Sections 70178, 70186
(A) : 4 students
(B) : 6 students
(C) : 3 students
(D) : 29 students
(E) : 1 student