20171220

Online reading assignment question: advice to future students

Astronomy 210, fall semester 2017
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. The following question was asked after the last lecture, but prior to the final exam.

Tell a student who is about to take this course next semester what he/she needs to know or to do in order to succeed in this course. (Graded for completion.)
"Study previous exams, review chapters after reading them once. Take notes while reading on flashcards. Ask questions! Review class assignments prior to going to class."

"Before each quiz do the quiz question packets--that is the best way to study for the quizzes, and also go to all of the classes. P-dog does really well at explaining everything."

"Make it to class, do the online reading assignments, spend time reading, get involved. Your teacher is there to help you."

"Do reading assignments in advance before class. Attend all class lectures and pay attention. Take good notes and don't forget to study and review. Keep every quiz and use them to study for exams"

"Do the reading assignments on time."

"Study and go over the online presentations and reading assignments before class, it will make learning things much easier."

"Stay on top of the assignments and if anything seems confusing, like how much the website/blog is used, or the format of the practice quizzes, contact P-dog right away. He is there to help! He obviously enjoys teaching, that's refreshing. But if you get confusing about using the website/blog, ask, don't wait! (I'm still trying to decipher it all!)"

"Go to class!"

"One must do the reading assignments. It helps to identify the key points of the reading, and help clarify some questions before going to class."

"Do not forget about the online reading assignments, they can really hurt/help your grade."

"Reading assignments, show up to class, and study for the quizzes."

"Have a study buddy who knows what they're doing and can help you study for the tests. do online reading."

"Show up to class and participate in group assignments/practice quizzes."

"Study/prepare for the quizzes! They are essential in this class and will really help you know the material on tests!"

"Go to class! And don't be afraid to use the online resources. The quiz and test archives are there to help you succeed."

"I think learning how to use the starwheel would be a good skill to have. The starwheels can tell a lot about astronomy, and think that learning how to use the starwheel is important."

"Don't get caught up in all the various subjects. Eat this thing one bite at a time."

"Don't miss class, as the in-class assignments are fun, and will learn material better than reading the book. Keep quizzes and test (in-class assignments if possible) as they are great study material."

"Do not procrastinate. Do not give up. Every point you can gain is worth it. Whether you've maxed out your points and are using it as practice, or you're actually getting points for your final grade, don't waste any opportunity."

"Familiarize yourself with and make good use of the course website. And don't be afraid to ask the instructor lots of questions :)"

"Don't forget to do the reading assignments and study for every quiz."

"Make sure you do the reading assignments, and go to class and take the quizzes. "

"Come to class, do these assignments, and try (but fail no matter how hard you try) to grow a better mustache than P-dog."

"Read. It really helps."

"Go to class, do the online work, talk to the people in your groups, and be grateful this is a chill-ass astronomy class."

"You need to actually study and do the reading assignments."

Online reading assignment question: advice to self for next semester

Physics 205A, fall semester 2017
Cuesta College, San Luis Obispo, CA

Students have a bi-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. The following question was asked after the last lecture, but prior to the final exam.

Give a piece of advice to yourself at the start of next semester on what you should do (the same, or differently) in order to succeed in Physics 205A/B (or similar science courses). (Graded for completion.)
"Attend class, that definitely keeps you up with the material, and helps a lot in the tests. Doing the homework cautiously and just studying a lot too!"

"Study for your midterms because I got 60/75 on each one."

"Show up, go to lab, do homework assignments, and just do what you usually would to succeed in a course."

"Keep up/ahead on reading assignments and attendance from early on the semester."

"Meet with a study group and a tutor more often."

"Showing up everyday helps! I didn't really need the textbook except for occasional reference."

"You should continue to do all the assigned homework, you should study for the quizzes and midterms. You should take more time to fully go through the textbook so that you can better understand the material."

"Do all the homework, labs, and quizzes this will help a lot in the course. Study, study, study."

"Just make time to do the online homework and reading. It really isn’t that bad or difficult. Just quit procrastinating and you’ll be fine."

"Keep doing the homework and going to class. But honestly read more and do more practice problems to be familiar with everything in the problem."

"Practice problems often. Review notes online on the blog and talk with the teacher and embedded tutor often."

"Keep up on the post-lab reports."

"Make an outline that briefly, but accurately expresses the main topics for each concept. Practice using the equations for each concept and apply the equations to your understanding of the topic."

"Don't be afraid to get a tutor for this class."

"Not taking course."

"Don’t procrastinate so much, and actually study more."

"Practice prior year's quizzes and exams! Also, really know each equation, what it is used for, and what the symbols in the equation stand for. "

"I would advise myself to study more about the laws and things that make something true in physics (for example newtons laws). I would also say don't just learn that something works because of something, learn why it works because of that specific thing."

"You've got it! Stop freaking out, be constant and anticipate!"

20171214

Physics quiz question: expansion of aluminum rod

Physics 205A Quiz 7, fall semester 2017
Cuesta College, San Luis Obispo, CA

An aluminum bar (linear expansion coefficient 2.3×10–5 K–1) has a length of 1.0000 m at 20.0° C. It will have a length of 1.0001 m at:
(A) 4° C.
(B) 16° C.
(C) 20.4° C.
(D) 24° C.

Correct answer: (D)

The relation between the change in length ∆L due to a temperature change ∆T is given by:

α·∆T = ∆L/L,

such that with an increase in length of ∆L = +0.0001 m, then:

T = ∆L/(α·L) = (+0.0001 m)/((2.3×10–5 K–1)·(1 m)) = +4.347826087 K,

or to one significant figure, the change in temperature is +4 K or +4° C, and so the bar will stretch by 0.0001 m when the temperature is 20.0° C + 4° C = 24° C.

(Response (A) is ΔT; response (B) is 20.0° C – ΔT; response (C) is 20.0° C + (ΔT/10).)

Sections 70854, 70855
Exam code: quiz07Whu7
(A) : 6 students
(B) : 2 students
(C) : 12 students
(D) : 22 students

Success level: 52%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.59

Physics quiz question: comparing final temperatures

Physics 205A Quiz 7, fall semester 2017
Cuesta College, San Luis Obispo, CA

An aluminum sample and an iron sample have the same mass and same initial temperature, and are kept separated from each other. Specific heat of aluminum is 900 J/(kg·K); specific heat of iron is 452 J/(kg·K). If the same amount of heat is transferred to each sample, the __________ sample will have a higher final temperature.
(A) aluminum.
(B) iron.
(C) (There is a tie.)
(D) (Not enough information is given.)

Correct answer (highlight to unhide): (B)

The transfer/balance energy conservation equation for each of these systems are given by:

Qext = ∆Ealuminum = maluminum·caluminum·ΔTaluminum,

and:

Qext = ∆Eiron = miron·ciron·ΔTiron.

For each sample and its corresponding equation, the mass m and heat Qext transferred is the same, so:

Qext = Qext,

maluminum·caluminum·ΔTaluminum = miron·ciron·ΔTiron,

caluminum·ΔTaluminum = ciron·ΔTiron,

and since caluminum > ciron, then ΔTaluminum < ΔTiron, and:

ΔTaluminum < ΔTiron,

(Taluminum,fTaluminum,0) < (Tiron,fTiron,0),

and since both samples have the same initial temperature Taluminum,0 = Tiron,0:

Taluminum,f < Tiron,f,

thus the iron sample will have the higher final temperature.

Sections 70854, 70855
Exam code: quiz07Whu7
(A) : 25 students
(B) : 13 students
(C) : 4 students
(D) : 0 students

Success level: 31%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.36

Physics quiz question: comparing changes in internal energies

Physics 205A Quiz 7, fall semester 2017
Cuesta College, San Luis Obispo, CA

An aluminum sample and an iron sample have the same mass. The aluminum sample initially has a higher temperature than the iron sample, and then they are brought in contact with each other to reach thermal equilibrium. Ignore heat exchanged with the environment. Specific heat of aluminum is 900 J/(kg·K); specific heat of iron is 452 J/(kg·K). After thermal equilibrium is reached, the __________ sample will have experienced the greatest change in internal energy.
(A) aluminum.
(B) iron.
(C) (There is a tie.)
(D) (Not enough information is given.)

Correct answer (highlight to unhide): (C)

The transfer/balance energy conservation equation for this system is given by:

Qext = ∆Ealuminum + ∆Eiron,

where for an isolated system, Qext = 0, so:

0 = ∆Ealuminum + ∆Eiron,

–∆Ealuminum = ∆Eiron.

This means that the aluminum sample experienced the same amount of thermal internal energy change (a decrease) as the change in the thermal internal energy of the iron sample (an increase).

Sections 70854, 70855
Exam code: quiz07Whu7
(A) : 7 students
(B) : 14 students
(C) : 19 students
(D) : 2 students

Success level: 45%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.31

Physics quiz question: thermal conductivity of bubble wrap

Physics 205A Quiz 7, fall semester 2017
Cuesta College, San Luis Obispo, CA

"Bubble Wrap"
Chrysti Hydeck
flic.kr/p/4wMG9t

A sheet of plastic bubble wrap (area of 0.56 m2, and thickness of 0.0065 m) has a thermal resistance of 0.43 K/watt[*]. The thermal conductivity of bubble wrap is:
(A) 0.0016 watts/m·K.
(B) 0.0050 watts/m·K.
(C) 0.027 watts/m·K.
(D) 37 watts/m·K.

[*] me.umn.edu/courses/me4054/archives/2013_Spring/S13_Design_Reports/S13%20Cushion%20V2.pdf.

Correct answer (highlight to unhide): (C)

The thermal resistance R of an object can be related to its thermal conductivity κ by:

R = d/(κ·A),

where d is the thickness of the object that heat must conduct through, and A is the cross-sectional area, such that the conductivity is given by:

κ = d/(R·A) = (0.0065 m)/((0.43 K/watt)·(0.56 m2)) = 0.02699335548 watts/m·K,

or to two significant figures, the thermal conductivity of the wall is 0.027 watts/m·K.

(Response (A) is d·R·A; response (B) is R/(A·d); response (D) is R·A/d).)

Sections 70854, 70855
Exam code: quiz07Whu7
(A) : 4 students
(B) : 3 students
(C) : 30 students
(D) : 5 students

Success level: 71%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.53

Physics quiz question: rate of heat radiated by the sun

Physics 205A Quiz 7, fall semester 2017
Cuesta College, San Luis Obispo, CA

Stars can be modeled as spherical blackbodies that radiate heat out to an environment assumed to have a temperature of 0 K. The sun has a surface temperature of 5,772 K and a surface area of 6.09×1018 m2. The sun radiates heat per time at a rate of:
(A) 3.45×1011 watts.
(B) 1.11×1015 watts.
(C) 1.99×1015 watts.
(D) 3.83×1026 watts.

Correct answer (highlight to unhide): (D)

The net power radiated by the sun (where the negative sign indicates that heat is continuously leaving the surface of the sun) is given by:

Power = –e·σ·A·((T)4 – (Tenv)4),

where the emissitivity e = 1 (for an ideal blackbody), the Stefan-Boltzmann constant σ = 5.670×10–8 watts/(m2·K4), the surface area A = 6.09×1018 m2, the surface temperature T = 5,772 K, and the temperature of the environment is assumed to be Tenv = 0 K, such that the rate of heat radiated by the sun can be solved for:

Power = –(1)·(5.670×10–8 watts/(m2·K4)·(6.09×1018 m2)·((5,772 K)4 – (0)4),

Power = –3.832707188×1026 watts,

or to three significant figures, the rate of hate radiated per time from the sun is 3.83×1026 watts.

(Response (A) is A·σ; response (B) is T4; response (C) is e·σ·A·T.)

Sections 70854, 70855
Exam code: quiz07Whu7
(A) : 1 students
(B) : 3 students
(C) : 18 students
(D) : 20 students

Success level: 48%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.66

Online reading assignment: origin of life, are we alone? (SLO campus)

Astronomy 210, fall semester 2017
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 origin of life, a "Here Is Today" timeline, LEGO® washing tips and the extraterrestrial hypothesis.

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 theories and evidence used to test how single-celled organisms came to be on our planet was interesting since it's not something I've thought about since high school and it's cool trivia to remember."

"The fraction of the time humans existed in the world and having intelligence is so little. This means that the world was so very boring for very very very long time, rather than just having volcanoes exploding, etc."

"I've always been interested in discovering if life exists, out of this whole universe, there is no possible way that we are alone."

"Finding fossil remnants of single-cell colonies. It's amazing that we can still find cells that date back to over 3 billion years."

"It was mind-blowing to visually see how young we humans are compared to the universe."

"The 'Here is Today' website was very interesting, as it was cool to see how small we are in the timeline of this world."

"The 'Here is Today' website and the origin of life presentation. I think this is interesting because it puts our lives into perspective and how we're only a small sliver in the Earth's life."

"I found it interesting when you put in to perspective that humans are extremely recent newcomers to Earth."

"I found that the LEGO® washing thing was interesting, it makes me want to test it to see if it actually works. Also, I thought the 'Here is Today' webpage was neat."

"I thought the part about DNA and the chemical bases for all life on earth, was quite interesting. They were saying that a lifeform has a set of chemical codes called DNA, this is relevant to its parent lifeform, if that exists, and is also relevant to its environment and its own reactions and growth, to itself and surrounding habitate. I thought this was interesting because a lifeform can inheret DNA from a parent molecule, while can also adapt and evolve to its habitat due to environmental stratus."

"The slide comment: 'But to be completely honest, there will be one step in particular that has yet to be recreated or remnants to be found for, and we will be sure to point this out.' I really appreciated the academic honesty in this statement. That was interesting for me."

"I thought the Drake equation was the most interesting because of all the different factors that go into deciding if there is more life other than on Earth."

"The crop circle video from the early 2000s. Don't really think it's really another lifeform who made it, but it is interesting to say the least."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"What was confusing to me was the idea of different geologic time gaps taking less and less time to evolve. Not sure how it took longer to create single-cell organisms than for humans to evolve."

"Why did it take so long for single-cell organisms to become complex cells? I don't want to rush nature, but why did complex organisms start to show up at 0.6 billion years ago instead of an earlier time?"

"The Drake equation is really confusing, I don't understand it."

"The Drake equation, because of the many factors that are not accurate or either have no way of discovering."

"I started to get confused when all the crazy factors in the Drake equation to find out if we are alone (or not). This was confusing because these type of equations just frighten me at first."

"The Drake equation. There are just a lot of factors to keep track of."

"The choice for the 'fraction with intelligence' slide confused me, but that's basically it."

"Not much was that confusing, although just the sheer scales of the equations/fractions for the chance of us not being alone are mind-boggling."

"How radio signals can go in space, for thousands and millions of miles, I would think that radio signals would dissipate in the endless depth of space."

"The crop circle...like whaat?"

Briefly describe a difference between life and non-living things.
"Life is something that's able to reproduce, grow and made up of cells or multi living cells while non-living things do not have these factors such as rocks."

"Living things have cells that can evolve and change to adapt to the environment around them, unlike non-living things."

"Life is breathing, seeing, having experiences and adapting. When I think of non-living things I think of stillness."

"Non-living things are abiotic while living things are known as biotic."

"Living things should be able to to adapt to changes throughout its life and the things surrounding them."

"Non-living things are things that do not do anything to their environment."

"Life is living and non-living is well, non-living."

Rank the time it takes for each of the following to have occurred on Earth.
(Only correct responses shown.)
Time after the formation of Earth for single-cell life to arise: about 1 billion years [35%]
Time for the first types of simple single-cell life to evolve into fishlike creatures: about 3 billion years [65%]
Time for fishlike creatures to evolve into more complex land-based animals today: about 0.5 billion years [65%]

How important is it to you to know whether or not there may be life elsewhere other than on Earth?
Unimportant.  [0]
Of little importance.  ** [2]
Somewhat important.  ********** [10]
Important.  ********** [10]
Very important.  **** [4]

Briefly explain your answer regarding the importance of knowing whether there may be life elsewhere other than on Earth.
"It would be nice to discover other hospitable planets that are confirmed to at least host single-celled organisms, but it isn't something I'm holding my breath over."

"Finding life outside our planet is very important because this changes everything: our way of life, the way we see things, religion, etc. If we ever find lifeforms outside that are more intelligent and advanced than humans, it can be very dangerous and frightening."

"If it was possible for life to happen on Earth, there's gotta be life out there somewhere too."

"I mean it would be pretty cool but also very scary because what if they already know about us and just don't want to be found."

"I want to know simply because we don't know and it is such heavy question."

"It is important, but unless they come to us I won't see them in my lifetime."

"While it would be cool to know if there was more life out there, I'm not too sure if we should seek it out."

"It's important because eventually we won't be able to use Earth and we need to have a place. I feel like finding other life would be significant for learning."

"In order to better understand my real intended purpose here on earth, I need to know that we are not just some cosmic accident. I need to know the reason for being. Finding out that there is life elswhere in the universe would give me that; and I don't think I'm alone."

"I believe that there must be life out in the vast universe. I do not think it is relevant to Earth. We have our own planet, and have many problems to worry about. We should not be worried about whether or not there is alien life, our in the infinite universe. There are many people, beings, on our planet, that are already here, and they have neccesities too, like clean water to drink, and food to eat, and cures for common diseaes, like typhoid fever, polio, smallpox, AIDS, and Ebola. We should focus on Life on this planet, before we worry about aliens in space."

"Kinda cool but kinda creepy, idk."

Which type of star would be least likely to have a planet that could support life?
Massive.  ************ [12]
Medium-mass.  ** [2]
Low-mass (red dwarf).  ********** [10]
(Unsure/guessing/lost/help!)  ** [2]

Briefly explain your answer to the previous question (type of star least likely to have a planet that could support life).
"Massive stars will be too short lived for complex life to develop."

"I feel like massive stars would be too massive and bright and die too quickly for life to develop."

"Well, I'm assuming a medium-mass star would be ideal. A low-mass star would be living for a longer period of time; however it would not be very bright. A massive would be incredibly bright; however it would die off very quickly which would probably kill off whatever life would be existing."

"Low-mass stars live for a longer period of time but are much colder than other stars, even our star."

"Red dwarfs are so small they wouldn't have as much heat to give planets that orbit it that heat. Plus they are much smaller so less gravitational pull."

Describe what the Drake equation is used for.
"Estimating the number of advanced technological civilizations in the galaxy."

"The Drake equation multiplies many factors that reflect more and more restrictive conditions for an advanced technological civilization to arise...I think."

In your opinion, how plausible is it that the Chilbolton message is a reply from extraterrestrials?
Implausible.  * [1]
Not very plausible.  ************ [12]
Somewhat plausible.  *********** [11]
Very plausible.  * [1]
(Unsure/guessing/lost/help!)  * [1]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"I need help on the Drake equation."

"Do you believe in other lifeforms outside of our galaxy?"

"Do you believe there are other lifeforms out there? Or that we will ever discover any?" (Yes, both probably just very simple life. I'm waiting to be surprised, though.)

"There's a 24-hour live stream of 1990's cooking shows online--Julia Childs is often on there--big fan lol. She looks hella young here." (#wellhello)

"Lion or tiger?" (What's wrong with ligers and lions?)

"Are you doing anything wild for winter break? (More adventures with Mrs. P-dog and Slumberjack, the Sleeping Forester.)

"Thanks for the class." (#yourewelcome #itsjustmywayofbeingme)

20171213

Physics quiz archive: temperature, thermal equilibrium, heat transfer

Physics 205A Quiz 7, fall semester 2017
Cuesta College, San Luis Obispo, CA
Sections 70854, 70855, 73320, version 1
Exam code: quiz07Whu7


Sections 70854, 70855 results
0- 6 :  
7-12 :   ******* [low = 6]
13-18 :   *************
19-24 :   ******************* [mean = 18.9 +/- 5.4]
25-30 :   *** [high = 27]

Astronomy quiz question: matter produced by past stars?

Astronomy 210 Quiz 7, fall semester 2017
Cuesta College, San Luis Obispo, CA

Another star, in the past produced the:
(A) hydrogen in red dwarfs.
(B) helium in the sun's core.
(C) iron in your blood.
(D) Milky Way's dark matter.
(E) (More than one of the above choices.)
(F) (None of the above choices.)

Correct answer (highlight to unhide): (C)

Stars produce metals (elements heavier than hydrogen and helium) in their cores during their giant/supergiant phases, up through type Ia/II supernovae explosions. Along with their unused hydrogen, these metals are then scattered into the interstellar medium, which are then incorporated into later generations of stars (or planets). Since iron is the only metal listed above, it is the only choice produced by a star in the past. (Dark matter is thought to have existed from the very early stages of the universe onwards, in order to facilitate the formation and maintain the structural integrity of galaxies.)

Section 70158
Exam code: quiz07Sl0p
(A) : 2 students
(B) : 4 students
(C) : 10 students
(D) : 0 student
(E) : 21 students
(F) : 4 students
(No response: 2 students)

Success level: 28% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.38

Section 70160
Exam code: quiz07ni4N
(A) : 3 students
(B) : 0 students
(C) : 12 students
(D) : 0 students
(E) : 11 students
(F) : 2 students

Success level: 47% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.43