P-dog's blog: boring but important: 201210

20121030

Online reading assignment: static fluids

Physics 205A, fall semester 2012
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 static fluids.

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.

"Water pressure is pretty cool--more related to the calculus stuff I already know. Also as an architect-poser, I think hydrostatic pressure is important. Buoyancy is important too, but I won't be building boats I think."

"How a sphygmomanometer is able to measure blood pressure. To actually stop the blood flow with the pressure from the cuff and then release the pressure to hear the blood start to flow again....very interesting. I work in a physical therapy clinic and often times have to measure a patient's blood pressure."

"In the presentation preview that it shows the 'Man from Atlantis' withstanding pressure 20,000 feet underwater--that's a lot of pressure! Physics doesn't apply to such a man as that."

"Buoyancy is an interesting topic. I grew up around boats but never really understood the science behind them, and I would like to know more."

"Pressure does not have a direction it is scalar. This is interesting because I thought pressure was like force."

"Viewing living on Earth as on the bottom of an ocean of fluid called air."

"How the highest city in terms of elevation in the U.S. had an air pressure 30% lower than ours."

"Before taking blood from a donor, a drop of the blood is placed in a solution of known density. If the drop does not sink it is not safe for the person to give blood because the concentration of iron from red blood cells is too low."

"Density is really interesting, just because it's density."

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

"Formulas, dude. And how the shape of something in a fluid effects bouyancy."

"Why is pressure in pascals, and not mmHg or atm?" (They're all units of pressure, but pascals (or N/m²) is the preferred SI unit.)

"If the Greek letter ρ (rho) refers to the density of a submerged object, or the density of the fluid the object is in."

"I don't quite understand the pressure and why the air gets thinner at higher altitudes. I would like to hear more on this topic."

"Honestly, most things."

"These chapters weren't all that confusing."

"Buoyancy is confusing to me because I don't really understand what is being measured. I would benefit from some in-class discussion and/or examples."

"The difference in gauge pressure and absolute pressure."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"I have a really hard time reading the orange pen on the whiteboard." (Agreed--I'll switch to another whiteboard marker color, even though it's Halloween.)

"What was the coolest Halloween costume you ever had?" (When Mrs. P-dog and I won a first-place Madonna Inn bakery cake for the Madonnaween costume contest a few years ago.)

"I'm not sure what to ask today."

Online reading assignment: the Milky Way (SLO campus)

Astronomy 210, fall semester 2012
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 the Milky Way's shape, size and composition, spiral arm structure and formation, and the history of its formation.

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.

"Because of the interstellar medium of gas and dust between stars, we can only see a portion of a presumably larger Milky Way disk."

"The way the Milky Way keeps its spiral arms, because I knew it was a spiral galaxy, but I never knew the reason why."

"Persistence of vision explaining spiral arms, looks cool."

"Crazy that metals come from stardust. That we are made from it and almost everything in the galaxy is as well...it's like constant recycling."

"The history of the Milky Way Galaxy--because I was raised in a fairly conservative, religious environment in which many explanations as to why things happened consisted of 'because God did it.' I like to know how and why things work and where scientists believe they have come from. Though theories such as that represented in the monolithic collapse model may be incomplete, at least such potential explanations are based on astronomers' gathering observations and testing hypotheses."

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

"The mass of a galaxy--how can we measure such a vast thing?"

"Global clusters positions, and not being able to see their parallax. Is this because the interstellar medium?"

"This chapter is nuts."

If you did not have access to a mirror, what could you do to find out whether or not you're having a bad hair day while camping?

"Look at the reflection in water/cell phone/glasses." (14 responses.)

"Feel my hair." (5 responses.)

"Ask a friend." (5 responses.)

"Take a picture with a camera/smartphone."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"When will we get to visit the Bowen Observatory next?" (Immediately after class on November 28--weather permitting, of course.)

"My mind is officially blown." (Then I am doing my job correctly.)

"How high does your grade have to be to not take the final exam? Would your grade drop from not taking it or taking it and getting a bad grade?" (Your course points are always computed as a raw total, and not as an average, so it will never decrease. Whatever your total points are just before taking the final exam will be your course grade if you do not take it.)

"How can I do better in this class? Don't B.S. me P-dog!" (You should go through the flashcard questions while reading through the textbook, as well as the archived quizzes and exams for practice, and discuss your responses with me after class, during office hours, or via e-mail.)

"What was the coolest Halloween costume you ever had?" (When Mrs. P-dog and I won a first-place Madonna Inn bakery cake for the Madonnaween costume contest a few years ago.)

Online reading assignment: the Milky Way (NC campus)

"Seeing many stars in a strip around us, but very few stars in the directions perpendicular to this strip tells us so far that we live in a flattened disk-shaped galaxy."

"Gravity is spread out over the Milky Way. I thought it would be condensed."

"The animation of the larger galaxy consuming a smaller one and creating its spiral arms, as it helped me visually picture the process."

"Our galaxy is awesome! It's kind of like a cannibal because it 'eats' dwarf galaxies. And that's part of the reason why the Milky Way has spiral arms."

"How we aren't able to see our own galaxy. We have an idea of what it looks like, but there is no possible way that we could ever see exactly what it looks like. That blows my mind."

"I had never put together that the atoms formed by stars in our galaxy's past are the same atoms that make us up! Everything is connected!"

"The sun is not even centered in our galaxy. Makes me think that nothing is perfect."

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

"I just didn't really understand the correlation between the age of the stars and their 'metallicity.'"

"How can 'dark matter' be most of the mass of the Milky Way when it is nothing."

"It's hard to mentally visualize dark matter as a concept when it is literally not visible. We can't see it, but somehow it's there and it has mass."

If you did not have access to a mirror, what could you do to find out whether or not you're having a bad hair day while camping?

"Look at the reflection in water/cell phone/glasses." (11 responses.)

"Feeling your hair/waving your head around." (3 responses.)

"Asking my friends/looking at their reactions." (3 responses.)

"Look at the shape of your shadow."

"Have someone take a picture of you!"

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"Are there going to be more extra-credit assignments later in the semester" How can we get more extra credit?" (Yes. There will be more online surveys, as well as in-class movie reports, and haiku activities later this semester.)

"What got you interested in teaching astronomy, and how do you keep yourself motivated to teaching?" (I started teaching astronomy at UC-Davis (where I had already been teaching physics) one summer because all of the astronomers on that campus happened to be unavailable to teach that course. And as it turns out, astronomy is much enjoyable to teach because everyone finds it so awesome compared to, say, um, having to take physics.)

"I'm starting to feel overwhelmed with this overload of information...is there any way we can review more for quizzes during class?" (You should go through the flashcard questions while reading through the textbook, and discuss your responses with me after class, during office hours, or via e-mail. We will also set aside time in class later this semester to review for the second midterm.)

"Is there any way to start preparing for the final now?" (Do as well as you can on the quizzes and the second midterm, and then worry about preparing for the final exam when it comes.)

20121029

Astronomy current events question: Alpha Centauri B Earth-mass extrasolar planet

Astronomy 210L, fall semester 2012
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!)

Xavier Dumusque et al., "Planet Found in Nearest Star System to Earth," October 16, 2012
http://www.eso.org/public/news/eso1241/

The European Southern Observatory's La Silla Observatory in Chile discovered an Earth-mass planet by observing __________ the nearby star Alpha Centauri B.
(A) reflected light from.
(B) its gravitational pull on.
(C) the eclipses of.
(D) the parallax of.
(E) a dusty disk surrounding.

Correct answer: (B)

Student responses
Sections 70178, 70186, 70200
(A) : 10 students
(B) : 30 students
(C) : 8 students
(D) : 5 students
(E) : 3 students

Astronomy current events question: Pluto moon hazards

Kelly Beatty, "A Problem with Pluto's Moons," October 17, 2012
http://www.skyandtelescope.com/news/home/The-Problem-with-Plutos-Moons-174686031.html

Pluto's newly discovered moons P4 and P5 could present a danger for NASA's New Horizon's spacecraft when it visits Pluto in 2015 because they may:
(A) themselves be orbited by smaller moonlets.
(B) suddenly collide into Pluto without warning.
(C) not be reflective enough to be seen.
(D) contain highly radioactive materials.
(E) be sources of dangerous high-speed debris.

Correct answer: (E)

Student responses
Sections 70178, 70186, 70200
(A) : 7 students
(B) : 2 students
(C) : 4 students
(D) : 0 students
(E) : 46 students

Astronomy current events question: giant impact theory of the moon's formation

John Matson, "Giant Impact Theory of Lunar Formation Gains More Credibility," October 17, 2012
http://www.scientificamerican.com/article.cfm?id=moon-impact-theory

Two sets of researchers have independently proposed refinements of how the moon was formed from a large impact with a newly formed Earth by:
(A) drilling into the Chicxulub impact crater on Earth.
(B) analyzing moonquake data recorded by the Apollo moon landing missions.
(C) measuring the reflectance of neighboring asteroids.
(D) running computer simulation models.
(E) synthesizing new chemicals from the impact event.

Correct answer: (D)

Student responses
Sections 70178, 70186, 70200
(A) : 7 students
(B) : 7 students
(C) : 3 students
(D) : 28 students
(E) : 12 students

20121028

Online reading assignment: forces and rotations

Physics 205A, fall semester 2012
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 rotations.

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.

"Torque and energy use the same SI units, but only one of them can be measured in joules."

"As an aspiring physical therapist, it is interesting to see how these concepts apply to biomechanics."

"How several different forces acting on an object each produce torque, and therefore adding them together you find the overall (net) torque on the object."

"It's possible for the net force acting to be zero while the net torque is nonzero."

"I feel that by the end of this class, I'll know the whole Greek alphabet."

"Nothing really, I am taking statics and this stuff about forces and moments (torques) is familiar to me."

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

"This whole lever arm thing--I didn't get it in statics and I don't understand it in physics."

"Nothing seemed to be confusing. However I did feel that the static equilibrium chapter wasn't the easiest section to read."

"The sign of the torque not being determined by the sign of the angular velocity, but determined by the sign of the angular acceleration."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"I came to your office hours before the last quiz and it didn't help me at all. If anything I would say I was thrown off. I would say that nearly half of what was talked about wasn't even on the quiz. What can we do about this?" (It's not my intent to mislead you in office hours, but I can only answer your questions and others' questions as time allows. Let me know what you yourself specifically need via e-mail, after class on Wednesdays, as well as office hours when they are less crowded.)

"How do you find all these awesome videos?" (I am online way too much for my own good. But if you have any cool physics video recommendations, let me know.)

"I am confused how the lab scores work. The syllabus says there is a possible 100 points for lab, but with the number of labs we at 5 points each we can't earn 100 points by the end of the semester." (In addition to the lab report points, each week there are two points from completing the online pre-lab and post-lab assignments, for a total of 13 labs × 7 points = 91 points, which do not include additional points for early report submission, and challenge activity points.)

20121025

Physics quiz question: train buffer stop

Physics 205A Quiz 4, fall semester 2012
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 6.13

"Rawie Buffer Stop 10 ZEB 8 Holanda Composição de 1430ton a 10 kmh"
Mundo Ferroviário
youtu.be/FmVSUl3cI5U

A 850,000 kg passenger train traveling at 4.2 m/s on a horizontal track pushes up against an end-of-track buffer stop[*]. As a result, the buffer stop brings the passenger train to a complete rest after traveling 7.0 m. Neglect friction and drag. The magnitude of the average force exerted by the buffer stop on the train is:
(A) 2.6×10⁵ N.
(B) 1.1×10⁶ N.
(C) 2.1×10⁶ N.
(D) 5.8×10⁷ N.

[*] "The buffer stop is designed to move up to 7 m to slow down a 850 t passenger train from 15 km/h," wiki.pe/File:Buffer_stop_zurich.jpg.

Correct answer (highlight to unhide): (B)

The non-conservative work done by the buffer stop (considered as an external agent outside of the train's energy systems) decreases the train's translational kinetic energy:

W_nc = ∆KE_tr,

where the work done is the product of the average force exerted and the displacement:

W_nc = F_av·s·cosθ,

such that the average force is:

F_av·s·cosθ = ∆KE_tr,

F_av = ∆KE_tr/(s·cosθ),

F_av = (1/2)·m·(v_f² – v₀²)/(s·cosθ),

F_av = = (1/2)·(850,000 kg)·((0 m/s)² – (4.2 m/s)²)/((7.0 m)·cos(180°)) = 1,071,000 N,

or to two significant figures, the magnitude of the force is 1.1×10⁶ N.

(Response (A) is (1/2)·m·v₀/(2·s); response (C) is m·v₀²/s; response (D) is m·g·s.)

Sections 70854, 70855
Exam code: quiz04Bmw3
(A) : 7 students
(B) : 20 students
(C) : 17 students
(D) : 7 students

Success level: 38%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.80

Physics quiz question: BMW 328i versus Cadillac ATS

Physics 205A Quiz 4, fall semester 2012
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 6.71

A 2013 BMW 328i (mass 1,545 kg) takes 7.7 s to accelerate from 22 m/s to 31 m/s on a horizontal track, while a 2013 Cadillac ATS (mass 1,577 kg) takes 8.6 sec to do so(*). Which car's engine has the greater average mechanical power output? Ignore friction and drag.
(A) BMW 328i.
(B) Cadillac ATS.
(C) (There is a tie.)
(D) (Not enough information is given.)

(*) Source: "BMW 328i curb weight: 3390 pounds, top gear, 50-70 mph: 7.7 sec; Cadillac ATS curb weight 3477 pounds, top gear, 50-70 mph: 8.6 sec," http://media.caranddriver.com/files/2013-bmw-328i-vs-2013-cadillac-ats2013-cadillac-ats-and-2013-bmw-328i-comparo.pdf.

Correct answer: (A)

The mechanical output of the cars' engines does non-conservative work to increase translational kinetic energy:

W_nc = ∆K,

where the average power output of the cars' engines is the rate of work done per time:

P_av = W_nc/∆t = ∆K/∆t.

For the BMW 328i, the engine power output is:

P_av = (1,545 kg)·((31 m/s)² - (22 m/s)²)/(7.7 s) = 9.6×10⁴ watts,

And for the Cadillac ATS, the engine power output is:

P_av = (1,577 kg)·((31 m/s)² - (22 m/s)²)/(8.6 s) = 8.7×10⁴ watts.

Thus the engine BMW 328i has the greater power output. (Note that the Cadillac ATS has the greater increase in kinetic energy, due to its greater mass, but will have a lower engine power output because of the longer time required for it to accelerate from 22 m/s to 31 m/s.)

Sections 70854, 70855
Exam code: quiz04Bmw3
(A) : 40 students
(B) : 10 students
(C) : 2 students
(D) : 0 students

Success level: 77%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.33

Physics quiz question: aircraft carrier steam catapult

Physics 205A Quiz 4, fall semester 2012
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 7.7

"F/A-18E-F Super Hornet Catapult Launches"
AiirSource
youtu.be/BHdz9hcccpw

A steam catapult on an aircraft carrier can launch a stationary airplane (mass 20,000 kg) to a speed of 74 m/s in 2.0 s[*]. The magnitude of the impulse exerted on the airplane is:
(A) 37 N·s.
(B) 7.4×10⁵ N·s.
(C) 1.5×10⁶ N·s.
(D) 5.5×10⁷ N·s.

[*] "45,000-pound plane from 0 to 165 miles per hour in two seconds," science.howstuffworks.com/aircraft-carrier3.htm.

Correct answer (highlight to unhide): (C)

The impulse J can be calculated as the initial-to-final change in momentum:

J = ∆p = m·∆v,

where ∆v = v_f – v₀, and assuming that the plane is moving in the +x direction after being catapulted (such that v_f = +74 m/s):

J = (20,000 kg)((+74 m/s) – (0 m/s)) = +1,480,000 N·s,

or to two significant figures, the magnitude of the impulse on the plane is 1.5×10⁶ N·s.

(Response (A) is the magnitude of the acceleration, response (B) is the magnitude of the net force, response (D) is the initial kinetic energy.)

Sections 70854, 70855
Exam code: quiz04Bmw3
(A) : 2 students
(B) : 16 students
(C) : 32 students
(D) : 2 students

Success level: 62%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.87

Physics quiz question: elastic collision

Physics 205A Quiz 4, fall semester 2012
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 7.49

In an elastic collision, two objects:
(A) rebound with no deformation.
(B) rebound after unsticking, with some deformation.
(C) are stuck together with no deformation.
(D) are stuck together and are permanently deformed.

Correct answer: (A)

In an elastic collision, the total kinetic energy of the colliding objects is conserved. The objects cannot stick together nor be permanently deformed after the collision, as this would indicate the loss of some kinetic energy.

Sections 70854, 70855
Exam code: quiz04Bmw3
(A) : 45 students
(B) : 6 students
(C) : 1 student
(D) : 0 students

Success level: 87%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.57

Physics quiz question: Cadillac ATS and BMW 328i collision

Physics 205A Quiz 4, fall semester 2012
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 7.47

(Ignore friction, drag, and other external forces during this brief collision.) A 2013 Cadillac ATS (mass 1,577 kg) traveling 12 m/s hits a stationary 2013 BMW 328i (mass 1,545 kg)[*]. Neither driver applies the brakes. Based solely on the information given, __________ must be conserved.
(A) momentum.
(B) translational kinetic energy.
(C) (Both of the above choices.)
(D) (None of the above choices.)

[*] "Cadillac ATS curb weight 3477 pounds; BMW 328i curb weight: 3390 pounds," media.caranddriver.com/files/2013-bmw-328i-vs-2013-cadillac-ats2013-cadillac-ats-and-2013-bmw-328i-comparo.pdf.

Correct answer (highlight to unhide): (A)

Negligible net external force and brief time duration for this collision makes the external impulse on this system zero, such that momentum is conserved. Since no information is given whether there is permanent deformation of both cars after the collision, it is not possible to determine if this is an elastic collision (such that translational kinetic energy is conserved) or an inelastic or completely inelastic collision (such that translational kinetic energy is not conserved). Without additional information regarding the resulting permanent deformation (if any) of the two cars after the collision, only momentum can be said to be conserved.

Sections 70854, 70855
Exam code: quiz04Bmw3
(A) : 37 students
(B) : 3 students
(C) : 11 students
(D) : 1 student

Success level: 72%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.87

Physics quiz question: bullets fused in mid-air

Physics 205A Quiz 4, fall semester 2012
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 7.43

(Consider that the net external force is negligible compared with the forces the objects exert on each other during these brief collisions.) Two bullets of slightly different masses travel towards each other with different speeds, and collide horizontally in mid-air, fusing together as a result(*). Based solely on the information given, what must be conserved?
(A) Momentum.
(B) Kinetic energy.
(C) (Both of the above choices.)
(D) (None of the above choices.)

(*) Source: "French and Russian Bullets Collided in Flight," http://paradoxoff.com/french-and-russian-bullets-collided-in-flight.html.

Correct answer: (A)

Negligible net external force and brief time duration for this collision makes the external impulse on this system zero, such that momentum is conserved. Since the two bullets fuse together, this is a perfectly inelastic collision, such that kinetic energy is not conserved.

Sections 70854, 70855
Exam code: quiz04Bmw3
(A) : 37 students
(B) : 2 students
(C) : 8 students
(D) : 5 students

Success level: 72%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.63

Physics quiz archive: energy conservation, momentum conservation

Physics 205A Quiz 4, fall semester 2012
Cuesta College, San Luis Obispo, CA
Sections 70854, 70855, version 1
Exam code: quiz04Bmw3

Sections 70854, 70855 results

0- 6 :
7-12 :	******** [low = 9]
13-18 :	**********
19-24 :	****************** [mean = 21.3 +/- 6.0]
25-30 :	**************** [high = 30]

20121024

Online reading assignment: medium-mass stars, massive stars, neutron stars and black holes (SLO campus)

Astronomy 210, fall semester 2012
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 the evolution of medium-mass stars, massive stars, and on neutron stars and black holes.

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.

"Star death is interesting to me because I think it is crazy that it even happens!"

"If you jumped at a black hole you would appear to fall forever. This doesn't make sense to me and I'm wondering how long you are actually falling for."

"Stars steal hydrogen from each other to create explosions. It was interesting to me because I did not know how that process worked."

"Red giant stage stars can lose mass due to strong stellar winds. That puts the Big Bad Wolf to shame. I think this is personally interesting for me because I never imagined there being wind in outer space--this is definitely leading me to reconsider my travel plans."

"Stars have several ways they can end. And pretty crazy that all life comes from star dust."

"White dwarfs are not really stars but are actually considered compact objects. I also found it a little disconcerting that as our sun begins to die all the matter on earth will be incinerated by the growing size of the sun and ultimately no chance will exist to sustain life on our planet. Fortunately, this will not happen for another couple of billion years so I do not have to add this to my list of things on my plate to concern myself with."

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

"How they can figure out how stars are made even though we cant get close to them."

"How a nova and a type Ia supernova occur. I don't understand how a star can just suck hydrogen out of another star."

"Black holes. I don't understand how the core of a star become small enough, (the radius of zero?), that the escape velocity in a region around it is so large that light cannot escape. What? Where does the object 'fall to' if it's a hole?"

"[Medium-mass] main sequence stars becoming giants is confusing. I thought that once a star died it was dead and couldn't become another star."

The first rule of astronomy class is...

"Don't talk about astronomy class." (2 responses.)

"Show up to class." (3 responses.)

"Sit still and ask lots of questions."

"Be a star. :3"

"Respect P-dog."

"P-Dog is the best." (2 responses.)

"Call you P-dog." (2 responses.)

"I don't know." (2 responses.)

"Have fun." (2 responses.)

"Abide by all of Cuesta's policies."

"Do not leave questions blank." (3 responses.)

"You are part of the universe and not just an observer."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"How do they know that a black hole is a hole if everything gets distorted and/or destroyed by tidal forces long before it even reaches the event horizon?"

"I feel like I'm in a dream within a dream whenever I go over astronomy stuff."

"Theoretically stars with masses larger than 15 solar masses form black holes when they die. Does that mean there's tons and tons of black holes?" (Yes, but massive stars are relatively rare compared to the more common medium-mass and low-mass stars in the universe, such that black holes would be vastly outnumbered.)

"Can we do something fun for Halloween? Like have a house party!" (We'll have a quiz. And then, there will be learning. What could possibly be more fun?)

20121023

Online reading assignment: rotational dynamics

Physics 205A, fall semester 2012
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 rotational dynamics.

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.

"There are different types of kinetic energy--translational and rotational. I assumed there was only one but I can see that we are going into more details."

"Depending on the distance in which a rotational axis is located, even with equal mass, the rotational energy can be greater due to a higher rotational inertia."

"Why choking up on a bat can give somebody more control over the swing. This is because the bat has a smaller rotational inertia."

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

"How two objects of the same mass rolling at the same speed do not necessarily have the same kinetic energy."

"The door with the hinges set in two different sides to rotate. Since the area of the door is the same it would seem that it would have the same rotational inertia."

"The equations for rotational inertia are especially complicated."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"I really like how the lectures are formatted with plenty of explanations and problem solving. I am really understanding the material. Good job!!!"

I cannot think of an instant where an object only has rotational energy and not translational." (Think of something that is spinning in place.)

"This is something I do not know much about, could we have a conceptual approach before just leaping into a formulaic approach." (These two approaches will go pretty much hand-in-hand.)

Astronomy current events question: Curiosity rover finds plastic shred on Mars

NASA/JPL press release, "Object Likely Benign Plastic from Curiosity Rover," October 9, 2012
http://mars.jpl.nasa.gov/msl/news/whatsnew/index.cfm?FuseAction=ShowNews&NewsID=1372

NASA's Mars Curiosity rover used its Chemistry and Camera (ChemCam) instrument to determine that a small, bright object found in its first sample scoop may be a:
(A) drop of supercooled water.
(B) shred of plastic material.
(C) natural type of diamond.
(D) fragment of an insect-like exoskeleton.
(E) crystal of feldspar or quartz.

Correct answer: (B)

Student responses
Sections 70178, 70186, 70200
(A) : 1 student
(B) : 16 students
(C) : 3 students
(D) : 0 students
(E) : 4 students

Astronomy current events question: analyzing Titan's surface from Huygen's landing data

Jia-Rui C. Cook and Markus Bauer, "Bounce, Skid, Wobble--How Huygens Landed on Titan," October 11, 2012
http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20121011.html

Scientists analyzing __________ data from the European Space Agency's Huygens probe have been able to measure the composition and consistency of the surface of Saturn's moon, Titan.
(A) fine-spectrum radar.
(B) infrared photographic.
(C) landing bounces and wobbles.
(D) liquid ethane and methane rainfall.
(E) core sample.

Correct answer: (C)

Student responses
Sections 70178, 70186, 70200
(A) : 2 students
(B) : 9 students
(C) : 37 students
(D) : 2 students
(E) : 2 students

Astronomy current events question: R Sculptoris spiral structure

Matthias Maercker, Wouter Vlemmings Onsala Space Observatory, Shazrene S. Mohamed, and Douglas Pierce-Price, "Surprising Spiral Structure Spotted by ALMA," October 10, 2012
http://www.eso.org/public/news/eso1239/

The Atacama Large Millimeter/submillimeter Array (ALMA) has discovered a spiral structure in the gas surrounding the star R Sculptoris, which European Southern Observatory scientists speculate may be caused by:
(A) the star's core suddenly collapsing.
(B) gravitational lensing.
(C) a central supermassive black hole.
(D) a hidden companion star.
(E) a bubble of dark matter.

Correct answer: (D)

Student responses
Sections 70178, 70186, 70200
(A) : 12 students
(B) : 7 students
(C) : 2 students
(D) : 26 students
(E) : 4 students

Astronomy current events question: Curiosity rover analysis of "Jake Matijevic" rock

DC Agle, Guy Webster, and Dwayne Brown, "Mars Rock Touched by NASA Curiosity has Surprises," October 11, 2012
http://www.nasa.gov/mission_pages/msl/news/msl20121011.html

NASA's Mars Curiosity rover used its Alpha Particle X-Ray Spectrometer (APXS) instrument and the Chemistry and Camera (ChemCam) instrument to determine that the "Jake Matijevic" rock is similar in composition to rocks:
(A) that formed deep in Earth's mantle.
(B) found in certain parts of Antarctica.
(C) embedded in asteroid impact craters.
(D) that are light enough to float on water.
(E) containing highly radioactive material.

Correct answer: (A)

Student responses
Sections 70178, 70186, 70200
(A) : 21 students
(B) : 0 students
(C) : 2 students
(D) : 2 students
(E) : 3 students

Online reading assignment: medium-mass stars, massive stars, neutron stars and black holes (NC campus)

Astronomy 210, fall semester 2012
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 the evolution of medium-mass stars, massive stars, and on neutron stars and black holes.

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.

"Expansion cooling was really cool! I think its awesome how a star can go from small to medium, to large, to super huge and then go boom! Supernova. It made me think of when you blow bubbles with chewing gum, once they get big enough they pop!"

"Space seems like an unforgiving place for a star. You die alone or you go out with a bang and take out other stars."

"I had always assumed, incorrectly, that a star is simply what it is. For instance, a white dwarf or a red giant--born a certain way and die in that same category--but this is incorrect. Stars go through changes, they evolve over time--like all living things. This fact helps to make the complex subject of stars more approachable."

"The death of stars, for no particular reason."

"'You, and the planet Earth, began as stardust and will end as stardust.' I found it to be interesting because its crazy to think that the world we live in will one day be gone. And what I found to be more crazy: how they worded that we as well started off as stardust. :("

"Black holes, because they're kind of a scary to think about and I didn't know too much about what they really are before reading about it!"

"The concept of black holes, and how if you jumped into one you would seem to be moving very slow by an outside observer."

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

"Recalling the differences between the stars: supergiants, nova, giants, white dwarfs... When I read them I feel I understand how they are all defined, but as I read the review questions it's like--OMG--what's this? :( More study, more memorizing. :)"

"How the companion star thing with supernovas worked."

"Differences between the types of supernova. It will be hard to memorize what produces each type."

"Black holes. Those are always confusing."

The first rule of astronomy class is...

"Don't talk about astronomy class." (Total of eight similar responses.)

"Have fun!"

"Always have pancakes =)"

"Don't do acid in class."

"Respect P-dog."

"Make sure that you don't get P-dog so mad that he collapses and explodes like a supernova. :p"

"Be able to explain your answers--not just if there's a right or wrong answer :/"

"Don't jump into any black holes."

"We are all apart of this universe we are studying and observing."

"Always try our best."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"What are good ways to memorizing the different stars and the different stages? Will we have to memorize the different types of novas?"(There will be two separate in-class activities on the different stages of stars, and on novae and type Ia supernovae of white dwarfs with close companion stars. Although not a substitute for reading the textbook, these in-class activities will be a good outline for review.)

"You've seen the movie Sunshine, right? I would recommend it if you haven't." (We already showed a clip from that movie in class!)

"Black hole or supernova--which would you prefer to witness, assuming you could survive both?" (A supernova, as you would then be able to report on what you experienced. Because even if you could survive falling into the event horizon of a black hole, you would never be able to communicate your experience to the rest of the universe.)

"What would be the best way to take notes in your class?" (Download the lecture slides, and make sure to preview the online presentation notes for the slides in connection with the textbook chapters, so you have at least a passing familiarity with the subject content. Then when we go over the presentation in class, you can concentrate on asking questions, and on taking notes on additional information in class not already covered in the online presentation notes.)

20121021

Online reading assignment: collisions

Physics 205A, fall semester 2012
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 something you found interesting from the assigned textbook reading or presentation preview, and explain why this was personally interesting for you.

"Collisions--I am a person that can't look away from a car crash, and I love Mythbusters, and watching things crash together, so that interests me."

"Only external interactions can change the total momentum in a system."

"How momentum is unchanged with a closed system only transferred."

"If you know muzzle velocity and mass of a bullet, and the mass of the gun you can calculate the recoil velocity. I shot a pretty freakin' large rifle in Africa, and it definitely had some recoil!"

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

"Having a hard time applying the momentum, impulse, and impulse-momentum theorem to the problems. I can't seem to figure out how to set them up."

"An isolated, or closed, system. This doesn't make too much sense to me because I don't see how this could actually happen--there are always going to be external forces acting on an object. Unless the object is in a zero-gravity, airless vacuum."

"Why linear momentum is always conserved for an isolated system."

"Keeping all the collision terms straight in my head. I kept mixing up what was elastic, perfectly inelastic, partially inelastic. The flow charts in the presentation helped me sort them out, but I still get the terms confused."

"So far, I am not sure how to do one of these kinds of problems because I have not known how to do one of these problems."

"I had assumed that when two objects collide, there would be some kinetic energy lost somehow. This isn't actually the case."

Briefly explain the conditions/assumptions under which momentum will be conserved for a collision.

"Frictionless surface, no air resistance."

"When external forces are zero. When there are no external forces involved."

"Collision must be brief where initial and final states are just before and after the collision (such that external impulse approaches 0)."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"Please go over momentum conservation." (Definitely.)

"Did you say earlier in the semester that if we had an 'A' going into the final exam that we didn't have to take it or was that from another class? I hope it was this one." (This is the class!)

"This seems way easier than the stuff we were learning before." (It does?)

20121018

Astronomy quiz question: HR 511

Astronomy 210 Quiz 4, fall semester 2012
Cuesta College, San Luis Obispo, CA

HR 511 is a star that is located 10 parsecs away from Earth. If HR 511 were moved to a location 12 parsecs away, its apparent magnitude m would __________, while its absolute visual magnitude M_V would __________.
(A) get dimmer; not change.
(B) get brighter; not change.
(C) not change; get dimmer.
(D) not change; get brighter.

Correct answer: (A)

The apparent magnitude of HR 511, which is the brightness as seen from Earth, will get dimmer as it is moved farther away from 10 parsecs to 12 parsecs. The absolute visual magnitude, which is the intrinsic brightness, will remain the same no matter where HR 511 is located.

Section 70158
Exam code: quiz04Spr6
(A) : 22 students
(B) : 1 student
(C) : 11 students
(D) : 1 student

Success level: 65% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.78

Astronomy quiz question: 61 Ursae Majoris

Astronomy 210 Quiz 4, fall semester 2012
Cuesta College, San Luis Obispo, CA

61 Ursae Majoris is a star that is located a distance 9.5 parsecs away from Earth, and has an apparent magnitude of m = +5.3. Its absolute magnitude M_V is:
(A) –5.3.
(B) 0.
(C) +5.2.
(D) +5.4.
(E) +9.5.

Correct answer: (D)

The apparent magnitude of Tau Ceti, which is the brightness as seen from Earth, will get dimmer as it is moved farther away from 9.5 parsecs to 10 parsecs. Since this is a very small increase in distance, then the absolute magnitude (its brightness at 10 parsecs away) would only be slightly dimmer than the apparent magnitude (its brightness at 9.5 parsecs away).

Section 70160
Exam code: quiz04nNm5
(A) : 3 students
(B) : 2 students
(C) : 8 students
(D) : 11 students
(E) : 2 students

Success level: 47% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.34

Astronomy quiz question: O5 main-sequence star versus K2 main-sequence star

Astronomy 210 Quiz 4, fall semester 2012
Cuesta College, San Luis Obispo, CA

An O5 main-sequence star will be __________ compared to a K2 main-sequence star.
(A) cooler and dimmer.
(B) cooler and brighter.
(C) hotter and dimmer.
(D) hotter and brighter.

Correct answer: (D)

On the OBAFGKM spectral type sequence, O-type stars are hotter than K-type stars, while on an H-R diagram, the O-type main sequence stars are brighter than the K-type main sequence stars.

Section 70158
Exam code: quiz04Spr6
(A) : 4 students
(B) : 0 students
(C) : 9 students
(D) : 22 students

Success level: 65% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.89

Section 70160
Exam code: quiz04nNm5
(A) : 2 student
(B) : 1 student
(C) : 4 students
(D) : 19 students

Success level: 75% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.14

Astronomy quiz question: nearby versus common visible stars

Astronomy 210 Quiz 4, fall semester 2012
Cuesta College, San Luis Obispo, CA

The majority of nearby stars are _________ the most common stars visible to the naked eye as seen from Earth.
(A) cooler and dimmer than.
(B) cooler and brighter than.
(C) hotter and dimmer than.
(D) hotter and brighter than.
(E) approximately the same temperature and brightness as.

Correct answer: (A)

The majority of nearby (and all stars in the Milky Way) are red dwarfs, while the most common stars visible to the naked eye are the distant but brighter and hotter massive main-sequence stars, giants and supergiants.

Section 70158
Exam code: quiz04Spr6
(A) : 18 students
(B) : 7 students
(C) : 2 students
(D) : 6 students
(E) : 2 students

Success level: 54% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.56

Section 70160
Exam code: quiz04nNm5
(A) : 17 students
(B) : 2 students
(C) : 1 student
(D) : 4 students
(E) : 2 students

Success level: 67% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.30

Astronomy quiz archive: sun/spectra/star properties

Astronomy 210 Quiz 4, fall semester 2012
Cuesta College, San Luis Obispo, CA

Section 70158, version 1
Exam code: quiz04Spr6

Section 70158

0- 8.0 :	*** [low = 4.0]
8.5-16.0 :	****
16.5-24.0 :	***********
24.5-32.0 :	******* [mean = 24.5 +/- 9.8]
32.5-40.0 :	********** [high = 40.0]

Section 70160, version 1
Exam code: quiz04nNm5

Section 70160

0- 8.0 :
8.5-16.0 :	** [low = 12.0]
16.5-24.0 :	*********
24.5-32.0 :	*********** [mean = 25.4 +/- 7.2]
32.5-40.0 :	**** [high = 40.0]

20121016

Online reading assignment: impulse and momentum

Physics 205A, fall semester 2012
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 impulse and momentum.

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.

"Intuitively it makes sense that when someone falls on concrete they will be more damaged than if they fall on padding. I thought it was interesting how the book explained that it happens because the momentum is changed gradually."

"I was unaware that cars have front ends that crush easily over a longer period of time, which decreases the amount of g's the driver or passenger will experience when in a collision. I just never thought about the affect that the change in stopping time can have on an object."

"Momentum can have multiple meanings not associated with physics."

Two objects moving at the same velocity but with different masses can have a different momentum."

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

"The impulse-momentum theorem."

"The concept of adding time to the force increases or decreases the momentum change on the objects involved."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"Can we please do many examples? :)" (As time allows, both instructor-led, and in student groups working on whiteboards.)

Online reading assignment: fusion, nebulae, star cluster ages (SLO campus)

Astronomy 210, fall semester 2012
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 fusion, nebulae, and star cluster ages.

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.

"Clouds of hydrogen gas can eventually form new stars and the dust around these stars can form into potential planets."

"The more massive the stars are more luminous they are because the must make more energy to support their weight, keeping them balanced. I didn't realize weight had to do anything with luminosity."

"Using cheerleaders to explain hydrogen fusion, because I am a cheerleader so it made me really excited!"

"All the stars in a star cluster are born at the same time. I always thought that stars formed more independently."

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

"It is all very confusing. I never really understand the material until we go over it in the following lecture, where the in-class activities help my grasp on each topic."

"Evolution rates of stars, but I think its because I have not had time to review the material comprehensively, but by class night I should have a better grasp of it."

"Nebulae because there are so many different types."

Briefly explain why "cold fusion" (producing energy from hydrogen fusion at room temperature) would be implausible.

"For hydrogen fusion to occur the gas particles have to be moving very rapidly, otherwise they will not collide with each other violently enough to fuse. Rapidly moving particles means high temperatures...very high temperatures! So this cannot happen at room temperature."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"The first midterm was not as bad as I thought it would be, I'm glad we had practice tests and question/chapter breakdowns to help study!" (Awesome.)

"Will there be more extra credit assignments?" (Yes, both online, and during review sessions.)

"P-dog is the illest chillest most real astronomy teacher in all of the lands."

Twitter: watching the two moons rise

"Incidental Comics: Steampunk Summer" (excerpt)
by Grant Snider
http://www.incidentalcomics.com/2012/06/steampunk-summer.html

Astronomy 210 Midterm 1, student 2210 response
Cuesta College, San Luis Obispo, CA
http://waiferx.blogspot.com/2012/10/astronomy-essay-question-watching-two.html

@patrick_m_len This is awesome! And apparently I need to enroll in some astronomy classes. :)
— Grant Snider (@grantdraws) October 15, 2012

Twitter: work habits of the moon and sun

"Doogie Horner's Flowchart: Work Habits of the Moon and Sun" (excerpt)
by Doogie Horner
http://boingboing.net/2012/03/16/doogie-horners-flowchart-wo.html

@doogiehorner infographic: work habits of the moon and sunboingboing.net/2012/03/16/doo… #astro101
— Patrick M. Len (@Patrick_M_Len) March 17, 2012

"hides behind clouds"? #astro101 #fail RT: @doogiehorner infographic: work habits of moon and sunow.ly/1IE6ME (via @patrick_m_len)
— Peter Newbury (@polarisdotca) March 17, 2012

@doogiehorner To me, your infographic suggest clouds cause Moon phases, a common misconception that #astro101 teachers strive to remedy.
— Peter Newbury (@polarisdotca) March 17, 2012

@doogiehorner Glad thats not what you meant. My spidey-senses tingle whenever I see Moon phases and clouds in the same sentence :)
— Peter Newbury (@polarisdotca) March 18, 2012

Astronomy current events question: Comet C/2012 S1 "ISON"

Kelly Beatty, "A 'Dream Comet' Heading Our Way?," September 27, 2012
http://www.skyandtelescope.com/community/skyblog/observingblog/A-Dream-Comet-Heading-Our-Way-171521041.html

Comet C/2012 S1 "ISON" is expected to be a bright "dream comet" in late 2013 into early 2014 because it:
(A) will pass extremely close to Earth.
(B) is the largest-ever comet yet discovered.
(C) will pass through several solar flares.
(D) is on a collision course with the sun.
(E) will pass in front of Comet Pan-STARRS.

Correct answer: (A)

Student responses
Sections 70178, 70186, 70200
(A) : 15 students
(B) : 5 students
(C) : 2 students
(D) : 1 student
(E) : 1 student

Astronomy current events question: "quasi-satellite" Plutino 15810

Camille Carlisle, "Pluto's Fake Moon," September 24, 2012
http://www.skyandtelescope.com/community/skyblog/newsblog/Plutos-Fake-Moon-170998771.html

Astronomers at the Universidad Complutense de Madrid have suggested that Plutino 15810 is a "quasi-satellite" of Pluto because it:
(A) closely leads or lags behind Pluto as they both orbit the sun.
(B) is too small to be considered a moon.
(C) passes back-and-forth between Pluto and its moon, Charon.
(D) is a fragment from a large impact on Pluto.
(E) does not have the same chemical composition as Pluto.

Correct answer: (A)

Student responses
Sections 70178, 70186, 70200
(A) : 20 students
(B) : 1 student
(C) : 4 students
(D) : 1 student
(E) : 0 students

Astronomy current events question: Hubble Space Telescope eXtreme Deep Field

NASA/European Space Agency press release, "Hubble Goes to the eXtreme to Assemble Farthest-Ever View of the Universe," September 25, 2012
http://www.nasa.gov/mission_pages/hubble/science/xdf.html

The NASA/European Space Agency Hubble Space Telescope eXtreme Deep Field (XDF) photograph of the most-distant galaxies ever imaged was obtained by:
(A) combining photographs of the same view over many years.
(B) gravitational lensing by nearby galaxies.
(C) using specialized polarizing fliters.
(D) advanced image-processing algorithms.
(E) searching in the x-ray region of the spectrum.

Correct answer: (A)

Student responses
Sections 70178, 70186, 70200
(A) : 33 students
(B) : 2 students
(C) : 4 students
(D) : 10 students
(E) : 1 student

Astronomy current events question: Martian streambed evidence

Guy Webster and Dwayne Brown, "NASA Rover Finds Old Streambed on Martian Surface," September 27, 2012
http://www.nasa.gov/mission_pages/msl/news/msl20120927.html

__________ is evidence of an ancient flowing stream recently discovered by NASA's Mars Curiosity rover.
(A) X-ray analysis of water-bearing minerals.
(B) Swirling patterns in sandstone.
(C) Downhill-branching channels.
(D) Gravel cemented in rock.
(E) Layers of evaporated salt.

Correct answer: (D)

Student responses
Sections 70178, 70186, 70200
(A) : 9 students
(B) : 5 students
(C) : 10 students
(D) : 24 students
(E) : 1 student

Online reading assignment: fusion, nebulae, star cluster ages (NC campus)

Astronomy 210, fall semester 2012
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 fusion, nebulae, and star cluster ages.

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.

"The steps of how fusion works and how it influences how the stars are."

"Stars have layers, and that the layers below support the ones above."

"Only main sequence stars follow the mass-luminosity relation because I would have thought that the giants and supergiants would follow due to their size."

"Any other nebulae colors besides pink, blue, black/brown seen in the outer space whether in a real or simulated view are either enhanced or false colors."

"Blue photons are scattered more easily than longer wavelengths and they enter you eyes producing the blue color we see in the sky. I've always been curious why the sky appears blue."

"The different stages of stars, also how long they can live."

"Stars we see now are not the same stars that our ancestors beheld. Stars live and die. This seems to be the one constant in life. Stars are, in a very real sense, animate beings. I find this extraordinary."

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

"Giant stars are large in diameter but not much larger in mass. I thought that would go hand-in-hand."

"Fusion. I don't understand why its so difficult to achieve."

"When talking about a star's age, is that a guess? It seems to me that it just has to be a really good guess."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"The review class we had really helped me with the midterm. :)" (Awesome.)

How do you come up with all of these crazy ways of explaining things? Like the house party model! It's all really entertaining while at the same time informative." (To quote Muriel Rukeyser from "The Speed of Darkness" (1968), "The Universe is made of stories, not of atoms." For me, stories and analogies are a powerful and compelling tool to understand complex concepts in science, and hopefully for you as well.)

"In one of the previous presentations you wrote, 'You may be the last generation of students that will actually understand these analogies.' Why?" (The model of magnetic fields trapping and stagnating convective granulation flow on the sun is analogous to holding a magnet next to a cathode-ray tube (CRT) television--which definitely does not work the same way for magnets and modern flat-screen televisions! As well as the incandescent light bulb model for the cooler and darker sunspots on the photosphere of the sun, which will soon be replaced by light-emitting diode (LED) bulbs...)

"What purpose do all of the stars have? Are they crucial to the universe as a whole?" (As we will see in a later presentation, we ourselves are made of atoms produced by earlier generations of stars. (Carl Sagan: "We're made of star-stuff. We are a way for the cosmos to know itself.")

20121014

Online reading assignment: energy forms and conservation

Physics 205A, fall semester 2012
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 energy forms and conservation.

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.

"Energy is only transformed into different forms, and is neither created nor destroyed."

"Dissipation of energy'' is used instead of saying 'something does work.'"

"Conservative forces such as gravity do not change mechanical energy, they just change from one form of mechanical energy into another."

"It takes the same amount of work to lift an object into the back of a truck or to roll it up a frictionless ramp as long as the vertical distance was the same."

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

"Conservative versus nonconservative forces."

"There are so many equations in this chapter, that I am confused with what I am supposed to do with all of them. I get the concept of energy, but at the same time, I felt like each section of reading was saying a different thing, which made me confused about what I was actually reading."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"Possibly have a review day before the quizzes where we go over and complete a practice quiz as a whole entire class?" (We can go over selected problems before a quiz, but you should complete the archived quiz for yourself, and come to office hours or e-mail me if you have problems.)

"What to do about this last midterm... I put so much 'energy' into it and got nothing in return. That was a total energy transfer that yearns to prove the law of conservation of energy wrong." (We'll discuss midterm scores and in-progress grade standings when midterms are handed back.)

"Is there an opportunity for extra credit besides from lab work?" (There will be several online extra-credit assignments later this semester.)

"Since I'm too lazy to look up the syllabus, is there a second midterm, and a cumulative final?" (Yes.)

Education research: introductory astronomy midterm statistics

Astronomy 210 Midterm 1, fall semester 2012
Cuesta College, San Luis Obispo, CA

Cuesta College Astronomy 210 (introductory astronomy lecture) students take their first midterm on cycles/motions, history of astronomy, and telescopes in the eighth week of instruction.

The midterm consists of ten multiple-choice questions (with partial credit for multiple-choice), and three short-answer questions (graded with a standardized rubric), to be completed within 80 minutes (the length of a regularly-scheduled lecture).

Grading statistics:
Section 70158
Exam code: midterm01sLa6

0- 20.0 :
20.5- 40.0 :	*** [low = 24.0]
40.5- 60.0 :	***************
60.5- 80.0 :	*********** [mean = 63.2 +/- 17.5]
80.5-100.0 :	********* [high = 96.5]

The order in which students turned in their completed midterms was recorded, beginning approximately 20 minutes after starting, to 80 minutes after starting. With a linear regression r² value of 0.2046, there is no significant correlation between the completion order c turning on the midterm and resulting score S (S = 0.6881c + 49.329).

Grading statistics:
Section 70160
Exam code: midterm01n4rN

0- 20.0 :
20.5- 40.0 :	** [low = 28.0]
40.5- 60.0 :	**********
60.5- 80.0 :	********** [mean = 66.8 +/- 18.3]
80.5-100.0 :	******** [high = 96.0]

With a linear regression r² value of 0.0125, there is no significant correlation between the completion order c turning on the midterm and resulting score S (S = 0.2438c + 63.446).

Education research: college physics midterm statistics

Physics 205A Midterm 1, fall semester 2012 Cuesta College, San Luis Obispo, CA Cuesta College Physics 205A (college physics, algebra-based, mandatory adjunct laboratory) students students take their first midterm on kinematics, Newton's laws, and circular motion in the eight week of instruction.

The midterm consists of five multiple-choice questions, two short-answer questions, and two worked-out problems, to be completed within 80 minutes (the length of a regularly-scheduled lecture).

Grading statistics:
Sections 70854, 70855
Exam code: midterm01sWFf

0-15 :
16-30 :	************ [low = 18]
31-45 :	******************* [mean = 42.3 +/- 12.2]
46-60 :	***********************
61-75 :	****** [high = 72]

The order in which students turned in their completed midterms was recorded, beginning approximately 20 minutes after starting, to 80 minutes after starting. With a linear regression r² value of 0.0123, there is no significant correlation between the completion order c turning on the midterm and resulting score S (S = 0.0876c + 39.797).

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