Anonymous, Cuesta College, San Luis Obispo, CA
But apparently cheap tricks like this works...on some level.
20070531
I will not come late to class
Anonymous, Cuesta College, San Luis Obispo, CA
But apparently cheap tricks like this works...on some level.
20070530
"Centrifugal absorption reciprocating" van
Centrifugal Absorption Reciprocating
Originally uploaded by Frauenfelder.
Physics 8A learning goal M2.1
The wondrous incongruity of it all!
20070529
"Let's Find Out About Air"
guvnor, Children's Books Photoshop Phriday contestSomethingAwful.com
Astronomy 10 learning goal Q4.1, Q4.5, Q5.3, Q5.4
Oddly amusing in this absurd mash-up that these children find studying air itself fascinating. Hopefully astronomy students will be directed to consider properties of "air" itself, as properties of the atmosphere will ultimately lead to a discussion on escape velocities, rms speeds, global warming, volcanism, sedimentation, plate tectonics, runaway greenhouse and runaway refrigerator effects.
The original book cover is delightfully even more surreal!
http://artlabo.ocnk.net/product/247
Assessment: discussion participation rubric
The NASA Center for Astronomy Education (CAE) hosts a listserver discussing astronomy teaching and learning, moderated by Gina Brissenden. Recent posting:
performing at a certain level (the Astronomy 10 grading rubrics (introductory general-education astronomy) and Physics 8AB grading rubrics (university physics, calculus-based) at Cuesta College are more specific, but similar to this rubric, stress transparency and objectivity for the benefit of the instructor, as well as the students.
The following table lists the criteria for posted in response to a topic on the discussion forum. The posted response should be with complete sentences and correct grammar. These will be graded according to the following:This rubric is a good example of a subtractive scale, where students understand that they will receive a certain grade for--Jean Hurrle, Kankakee River Valley Forest Preserve District
- 90-100: A-Level participation
- The conclusion or opinion is relevant to the discussion topic.
- The answer is insightful & synthesizes basic concepts.
- You have stated reasons and evidence to support your conclusion or opinion.
- The answer and supporting evidence is clearly stated.
- 80-89: B–Level participation
Same as A-Level participation, except that:
- The answer is notably lacking one of the items listed for an A level response.
- 70-79: C–Level participation
Same as B–Level participation, except that:
- The answer is notably lacking two of the items listed for A-Level response.
- 60-69: D-Level participation
Same as C–Level participation, except that:
- The answer is notably lacking three of the items listed for A- Level response.
- 59 and below: F–level participation
- Failure to turn in the work
Assessment: final exam weight
The NASA Center for Astronomy Education (CAE) hosts a listserver discussing astronomy teaching and learning, moderated by Gina Brissenden. Recent posting:
Typically the top student in the class does not need to take the Final Exam, having already earned an "A" grade by the last week of class. Over the past four years, two pre-final "A" students have taken the Final Exam even though it would not raise their grade any further (Cuesta College has no +/- grades) probably to see if they could get more than the maximum 600 points (which they did).
...Is telling your students "one blaze of effort at the end is all you really need to pass a college class" a message we should be sending? Especially if these will be future teachers? My finals are worth no more than any other test. The good news is students get to drop a test. So my best students never take the final.In Astronomy 10 (introductory astronomy, general education) at Cuesta College, the Final Exam is weighted no more than the midterms (but no exams are dropped), and a single exam (75 points) is worth less than a letter grade jump (100 points). This means that students are highly motivated to continuously keep up with the material during the semester as opposed to the "blaze of effort at the end," as their letter grade will nearly be pre-determined by the end of the semester, as the Final Exam can only raise their letter grade if they reasonably close to a cut-off.
-- Liam McDaid, Sacramento City College
Typically the top student in the class does not need to take the Final Exam, having already earned an "A" grade by the last week of class. Over the past four years, two pre-final "A" students have taken the Final Exam even though it would not raise their grade any further (Cuesta College has no +/- grades) probably to see if they could get more than the maximum 600 points (which they did).
20070525
Education research: SPCI gains (Cuesta College, Spring Semester 2006-Spring Semester 2007)
The Star Properties Concept Inventory was developed by Janelle Bailey as a pre-test and post-test for introductory astronomy courses. For an overview of how <g> quantifies gains in learning (Hake), see the previous post: Education research: FCI gains (Cuesta College).
The SPCI was administered to Astronomy 10 (one-semester introductory astronomy) students at Cuesta College, San Luis Obispo, CA during the first class meeting, then on the last class meeting. The results below are class averages for the initial and final SPCI scores (given as percentages, with standard deviations), as well as the Hake normalized gain <g>:
Because survey packets and forms were accidentally misplaced, the SPCI was not administered for section 4136 at the start of that semester, but these students were able to take the post-test at the end of the semester. While <g> cannot be calculated for that section 4136, note that the class average for their final SPCI scores is consistent with results from other sections.
There is no published data as of yet on comparing the relative gains on the SPCI across different learning environments or different institutions. SPCI results from another instructor at Cuesta College during the same time period (Fall 2006) may be compiled and available at a later date.
Astronomy 10 can be classified as an interactive engagement course by Hake's terminology, as students spend approximately a third of their instructional time in passive lectures, instead participating in peer-group written activities ("lecture-tutorials"), and individual and collaborative electronic response system activities ("clickers").
The SPCI was administered to Astronomy 10 (one-semester introductory astronomy) students at Cuesta College, San Luis Obispo, CA during the first class meeting, then on the last class meeting. The results below are class averages for the initial and final SPCI scores (given as percentages, with standard deviations), as well as the Hake normalized gain <g>:
Astronomy 10 Spring Semester 2007 section 4136
N = 36
<initial%> = ??% +/- ??%
<final%> = 50% +/- 16%
<g> = 0.??
Astronomy 10 Spring Semester 2007 section 5076
N = 32
<initial%> = 29% +/- 9%
<final%> = 49% +/- 15%
<g> = 0.29
Astronomy 10 Fall Semester 2006 section 1080
N = 61
<initial%> = 29% +/- 14%
<final%> = 49% +/- 14%
<g> = 0.29
Astronomy 10 Spring Semester 2006 section 5060
N = 47
<initial%> = 28% +/- 12%
<final%> = 50% +/- 11%
<g> = 0.32
Because survey packets and forms were accidentally misplaced, the SPCI was not administered for section 4136 at the start of that semester, but these students were able to take the post-test at the end of the semester. While <g> cannot be calculated for that section 4136, note that the class average for their final SPCI scores is consistent with results from other sections.
There is no published data as of yet on comparing the relative gains on the SPCI across different learning environments or different institutions. SPCI results from another instructor at Cuesta College during the same time period (Fall 2006) may be compiled and available at a later date.
Astronomy 10 can be classified as an interactive engagement course by Hake's terminology, as students spend approximately a third of their instructional time in passive lectures, instead participating in peer-group written activities ("lecture-tutorials"), and individual and collaborative electronic response system activities ("clickers").
- Bailey, J. M. (2006). "Development of a concept inventory to assess students' understanding and reasoning difficulties about the properties and formation of stars." Unpublished doctoral dissertation, University of Arizona, Tucson, AZ.
Development of the SPCI, a 30-question survey of stellar properties concepts (blackbody radiation laws). - R.R. Hake, "Interactive-engagement vs. traditional methods: A six-thousand-student survey of mechanics test data for introductory physics courses," Am. J. Phys. 66, 64 -74 (1998).
Definition of <g>, and relative comparison of many interactive engagement and traditional courses.
20070524
Education research: FCI gains (UC-Davis)
For an overview of how <g> quantifies the gains in learning Newtonian mechanics concepts (Hake), as measured by the Force Concept Inventory (Hestenes et al.), see the previous post: Education research: FCI gains (Cuesta College).
Physics 7B is the second quarter (fluid dynamics, electric circuits, kinematics, Newton's laws, rotational dynamics, momentum) of a reformed algebra-based interactive engagement course in introductory physics at the University of California, Davis. These students took the FCI during the first lab, and again during the last lab meeting during the second summer session in 2002:
Note that the class averages for both the initial and final FCI scores at UC-Davis are lower than at Cuesta College (41%-44%, and 49%-53% respectively), which would be expected from the different student populations at each institution (pre-medical/dental/veterinary students in algebra-based physics at UC-Davis; pre-engineering students in calculus-based physics at Cuesta College).
In contrast, the gains for either student populations are identical (0.16 for UC-Davis; 0.14-0.16 for Cuesta College), which classifies them both as "low-g" courses by Hake. This is particularly interesting for the Physics 7B course at UC-Davis, as Hake found that this type of course (interactive engagement) resulted in a <g> of 0.48 +/- 0.14 for the 4,832 students surveyed in his study. However, a summer session at UC-Davis is a quarter (10 week) course, of which only 40% of the course deals with translational kinematics and Newton's laws. As a summer session course compresses this timeline into five weeks, this means that UC-Davis students would only have two weeks during the summer session to construct, master, and consolidate a Newtonian understanding of mechanics, which apparently is not enough time, even in an interactive engagement environment.
What will be interesting is the forthcoming results from studying Physics 5A students at Cuesta College, starting Fall 2007, which is a more closely aligned population with UC-Davis Physics 7B students. Physics 5B is a traditional algebra-based introductory physics course, planned to be extensively augmented with interactive engagement learning techniques over the next two years.
Physics 7B is the second quarter (fluid dynamics, electric circuits, kinematics, Newton's laws, rotational dynamics, momentum) of a reformed algebra-based interactive engagement course in introductory physics at the University of California, Davis. These students took the FCI during the first lab, and again during the last lab meeting during the second summer session in 2002:
Physics 7B Summer Session II 2002 sections 21-23
N = 76
<initial%> = 30% +/- 13%
<final%> = 41% +/- 18%
<g> = 0.16
Note that the class averages for both the initial and final FCI scores at UC-Davis are lower than at Cuesta College (41%-44%, and 49%-53% respectively), which would be expected from the different student populations at each institution (pre-medical/dental/veterinary students in algebra-based physics at UC-Davis; pre-engineering students in calculus-based physics at Cuesta College).
In contrast, the gains for either student populations are identical (0.16 for UC-Davis; 0.14-0.16 for Cuesta College), which classifies them both as "low-g" courses by Hake. This is particularly interesting for the Physics 7B course at UC-Davis, as Hake found that this type of course (interactive engagement) resulted in a <g> of 0.48 +/- 0.14 for the 4,832 students surveyed in his study. However, a summer session at UC-Davis is a quarter (10 week) course, of which only 40% of the course deals with translational kinematics and Newton's laws. As a summer session course compresses this timeline into five weeks, this means that UC-Davis students would only have two weeks during the summer session to construct, master, and consolidate a Newtonian understanding of mechanics, which apparently is not enough time, even in an interactive engagement environment.
What will be interesting is the forthcoming results from studying Physics 5A students at Cuesta College, starting Fall 2007, which is a more closely aligned population with UC-Davis Physics 7B students. Physics 5B is a traditional algebra-based introductory physics course, planned to be extensively augmented with interactive engagement learning techniques over the next two years.
20070523
Education research: FCI gains (Cuesta College)
Richard R. Hake quantifies gains made by first-year students in taking the Force Concept Inventory (Doug Hestenes, et al.) in terms of the average normalized gain <g>:
<g> = (final FCI class average - initial FCI class average)/(100% - initial FCI class average)
which represents the possible amount that a class can raise their average FCI score from the start of the semester to the end of the semester. E.g., if the initial FCI class average is 40%, then the maximum gain achievable is 60%; thus a final FCI class average of 40% represents a <g> = 0 (no gain), a final FCI class average of 70% represents a <g> = 0.5 (half of the maximum achievable gain), and a final FCI class average of 100% represents a <g> of 1.0.
Hake goes on to classify courses in terms of <g>:
In Hake's words, interactive engagement courses:
The low <g> for these past three semesters comes as no surprise, as this course was taught using traditional passive lectures and "cookbook" labs.
However, the initial class average FCI scores at Cuesta College are encouragingly high to begin with (ranging from 41% to 44%, N = 135), compared to the colleges (39%, N = 597) and universities (48%, N = 4,832) surveyed by Hake.
It is hoped that at Cuesta College, future use of electronic response systems ("clickers," from einstruction.com) and interactive whiteboards (Ubiquitous Presenter on Tablet PCs) over the next two years will result in better student learning of introductory physics, as reflected in higher <g> values.
<g> = (final FCI class average - initial FCI class average)/(100% - initial FCI class average)
which represents the possible amount that a class can raise their average FCI score from the start of the semester to the end of the semester. E.g., if the initial FCI class average is 40%, then the maximum gain achievable is 60%; thus a final FCI class average of 40% represents a <g> = 0 (no gain), a final FCI class average of 70% represents a <g> = 0.5 (half of the maximum achievable gain), and a final FCI class average of 100% represents a <g> of 1.0.
Hake goes on to classify courses in terms of <g>:
"High-g" courses: <g> >= 0.7
"Medium-g" courses: 0.7 > <g> >= 0.3
"Low-g" courses: 0.3 > <g>
Interactive engagement courses (48 courses):
<g> = 0.48 +/- 0.14
Traditional courses (14 courses):
<g> = 0.23 +/- 0.04
In Hake's words, interactive engagement courses:
"...promote conceptual understanding through interactive engagement of students in heads-on (always) and hands-on (usually) activities which yield immediate feedback through discussion with peers and/or instructors."In contrast, traditional courses:
"...make little or no use of IE methods, relying primarily on passive-student lectures, recipe labs, and algorithmic-problem exams."The FCI was administered to Physics 8A (first-semester of calculus-based physics sequence) students at Cuesta College, San Luis Obispo, CA during the first week of instruction, then on the last week of instruction. The results below are class averages for the initial and final FCI scores (given as percentages, with standard deviations), as well as the Hake normalized gain <g>:
Physics 8A Spring Semester 2007 sections 4909-4911
N = 27
<initial%> = 41% +/- 17%
<final%> = 49% +/- 20%
<g> = 0.14
Physics 8A Fall Semester 2006 sections 0910-0912
N = 36
<initial%> = 42% +/- 21%
<final%> = 51% +/- 18%
<g> = 0.16
Physics 8A Spring Semester 2006 sections 4888-4893
N = 72
<initial%> = 44% +/- 21%
<final%> = 53% +/- 20%
<g> = 0.15
The low <g> for these past three semesters comes as no surprise, as this course was taught using traditional passive lectures and "cookbook" labs.
However, the initial class average FCI scores at Cuesta College are encouragingly high to begin with (ranging from 41% to 44%, N = 135), compared to the colleges (39%, N = 597) and universities (48%, N = 4,832) surveyed by Hake.
It is hoped that at Cuesta College, future use of electronic response systems ("clickers," from einstruction.com) and interactive whiteboards (Ubiquitous Presenter on Tablet PCs) over the next two years will result in better student learning of introductory physics, as reflected in higher <g> values.
- R.R. Hake, "Interactive-engagement vs. traditional methods: A six-thousand-student survey of mechanics test data for introductory physics courses," Am. J. Phys. 66, 64 -74 (1998).
Definition of <g>, and relative comparison of many interactive engagement and traditional courses. - D. Hestenes, M. Wells, and G. Swackhamer, Arizona State University, "Force Concept Inventory," Phys. Teach. 30, 141-158 (1992).
Development of the FCI, a 30-question survey of basic Newtonian mechanics concepts. - Physics Teacher Education Coalition: California Polytechnic State University, San Luis Obispo Project Report: September 2006
Implementation of interactive engagement methods at Cal Poly, using different assessment tools (Force and Motion Concept Evaluation, and other conceptual tests).
20070522
Supergiant simulation
Emergent surface intensity of a supergiant (*.mpg)
From Numerical simulations of a red supergiant
Bernd Freytag, Centre de Recherche Astronomique de Lyon and Uppsala Astronomical Observatory
Astronomy 10 learning goal M3.2
Computer simulation over several months of the outer layers of a supergiant, such as Betelgeuse, between its main sequence phase, and inevitable type II supernova explosion.
20070521
Astronomy quiz question: oldest white dwarfs
Astronomy 10 Quiz 12, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q12.3
[3.0 points.] Which one of the following choices best describes characteristics expected of the oldest white dwarfs in the disk of the Milky Way?
(A) On the verge of undergoing type Ia supernova explosions.
(B) Dim luminosities and cool surface temperatures.
(C) Extremely metal-rich absorption spectra.
(D) Extremely redshifted absorption spectra.
(E) Extremely low mass.
Correct answer: (B).
White dwarfs are the degenerately packed cores of giants, after the outer layers have been shed during the planetary nebula phase. Since there is no more energy source for an isolated white dwarf, it will gradually cool off and become dimmer in luminosity, according to the Stefan-Boltzmann law (luminosity proportional size times temperature^4), where size remains constant.
Student responses
Section 4136
(A) : 5 students
(B) : 16 students
(C) : 7 students
(D) : 5 students
(E) : 2 students
Section 5076
(A) : 1 student
(B) : 13 students
(C) : 6 students
(D) : 5 students
(E) : 1 student
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q12.3
[3.0 points.] Which one of the following choices best describes characteristics expected of the oldest white dwarfs in the disk of the Milky Way?
(A) On the verge of undergoing type Ia supernova explosions.
(B) Dim luminosities and cool surface temperatures.
(C) Extremely metal-rich absorption spectra.
(D) Extremely redshifted absorption spectra.
(E) Extremely low mass.
Correct answer: (B).
White dwarfs are the degenerately packed cores of giants, after the outer layers have been shed during the planetary nebula phase. Since there is no more energy source for an isolated white dwarf, it will gradually cool off and become dimmer in luminosity, according to the Stefan-Boltzmann law (luminosity proportional size times temperature^4), where size remains constant.
Student responses
Section 4136
(A) : 5 students
(B) : 16 students
(C) : 7 students
(D) : 5 students
(E) : 2 students
Section 5076
(A) : 1 student
(B) : 13 students
(C) : 6 students
(D) : 5 students
(E) : 1 student
20070518
Physics quiz question: no-work pressurization
Physics 8A Quiz 12, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Physics 8A learning goal Q12.4
[3.0 points.] Consider a system with a diatomic ideal gas where no work is done on or by the gas.
(Cf. Young and Freeman, University Physics, 11/e, Problem 17.101(a).)
[Version 1]
Which one of the following choices best describes the heat flow during this process, if the pressure increases?
(A) Heat flows into the system.
(B) No heat is transferred into/out of this system.
(C) Heat flows out of the system.
(D) (None of the above choices (A)-(C), as not enough information is given.)
Correct answer: (A)
If no work is done, there there is no area under this process path on a pV-diagram, thus this must be an isochoric process. From the ideal gas law, for pressure to increase (while volume remains constant), the temperature must increase. Then the first law of thermodynamics states:
+Q_in - W_out = delta(U),
where W_out = 0, delta(U) > 0, and thus +Q_in > 0, and heat was put into the gas.
Student responses:
(A) : 11 students
(B) : 2 students
(C) : 1 student
(D) : 1 student
[Version 2]
Which one of the following choices best describes the heat flow during this process, if the pressure decreases?
(A) Heat flows into the system.
(B) No heat is transferred into/out of this system.
(C) Heat flows out of the system.
(D) (None of the above choices (A)-(C), as not enough information is given.)
Correct answer: (C)
If no work is done, there there is no area under this process path on a pV-diagram, thus this must be an isochoric process. From the ideal gas law, for pressure to decrease (while volume remains constant), the temperature must decrease. Then the first law of thermodynamics states:
+Q_in - W_out = delta(U),
where W_out = 0, delta(U) < 0, and thus +Q_in < 0, and heat was taken out of the gas.
Student responses:
(A) : 2 students
(B) : 2 students
(C) : 5 students
(D) : 0 students
Cuesta College, San Luis Obispo, CA
Physics 8A learning goal Q12.4
[3.0 points.] Consider a system with a diatomic ideal gas where no work is done on or by the gas.
(Cf. Young and Freeman, University Physics, 11/e, Problem 17.101(a).)
[Version 1]
Which one of the following choices best describes the heat flow during this process, if the pressure increases?
(A) Heat flows into the system.
(B) No heat is transferred into/out of this system.
(C) Heat flows out of the system.
(D) (None of the above choices (A)-(C), as not enough information is given.)
Correct answer: (A)
If no work is done, there there is no area under this process path on a pV-diagram, thus this must be an isochoric process. From the ideal gas law, for pressure to increase (while volume remains constant), the temperature must increase. Then the first law of thermodynamics states:
+Q_in - W_out = delta(U),
where W_out = 0, delta(U) > 0, and thus +Q_in > 0, and heat was put into the gas.
Student responses:
(A) : 11 students
(B) : 2 students
(C) : 1 student
(D) : 1 student
[Version 2]
Which one of the following choices best describes the heat flow during this process, if the pressure decreases?
(A) Heat flows into the system.
(B) No heat is transferred into/out of this system.
(C) Heat flows out of the system.
(D) (None of the above choices (A)-(C), as not enough information is given.)
Correct answer: (C)
If no work is done, there there is no area under this process path on a pV-diagram, thus this must be an isochoric process. From the ideal gas law, for pressure to decrease (while volume remains constant), the temperature must decrease. Then the first law of thermodynamics states:
+Q_in - W_out = delta(U),
where W_out = 0, delta(U) < 0, and thus +Q_in < 0, and heat was taken out of the gas.
Student responses:
(A) : 2 students
(B) : 2 students
(C) : 5 students
(D) : 0 students
20070517
Astronomy clicker question: whence cosmic background radiation?
Astronomy 10, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q12.4
Students were asked the following clicker question (Classroom Performance System, einstruction.com) at the start of their learning cycle:
[0.3 points.] What is the cosmic background radiation?
(A) Photons that have always existed, even before the start of the big bang.
(B) Photons from the very start of the big bang.
(C) Photons from about 400,000 years after the start of the big bang.
(D) Photons from the end of gravitational deceleration (start of dark energy acceleration).
Correct answer: (C).
It was too hot for protons and electrons to form atoms in the early universe, until approximately 400,000 years after the start of the big bang. Since atoms scatter light less efficiently than separate protons and electrons, when the universe made this "recombination" or "decoupling" transition from an opaque to a much more transparent state, photons were effectively freed from this time forward. However, any photons from earlier, back to the start of the big bang, were effectively lost.
Student responses
Section 5076
(A) : 5 students
(B) : 7 students
(C) : 1 student
(D) : 6 students
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q12.4
Students were asked the following clicker question (Classroom Performance System, einstruction.com) at the start of their learning cycle:
[0.3 points.] What is the cosmic background radiation?
(A) Photons that have always existed, even before the start of the big bang.
(B) Photons from the very start of the big bang.
(C) Photons from about 400,000 years after the start of the big bang.
(D) Photons from the end of gravitational deceleration (start of dark energy acceleration).
Correct answer: (C).
It was too hot for protons and electrons to form atoms in the early universe, until approximately 400,000 years after the start of the big bang. Since atoms scatter light less efficiently than separate protons and electrons, when the universe made this "recombination" or "decoupling" transition from an opaque to a much more transparent state, photons were effectively freed from this time forward. However, any photons from earlier, back to the start of the big bang, were effectively lost.
Student responses
Section 5076
(A) : 5 students
(B) : 7 students
(C) : 1 student
(D) : 6 students
20070516
Astronomy clicker question: expanding universe evidence
Astronomy 10, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q12.2
Students were asked the following clicker question (Classroom Performance System, einstruction.com) at the start of their learning cycle:
[0.3 points.] How do we know that the universe is expanding?
(A) The distance from the Sun to the Earth is increasing.
(B) The speed of light is slowing down.
(C) Distant galaxies appear to be moving away faster than nearby galaxies.
(D) Distant galaxies appear to be much younger than nearby galaxies.
Correct answer: (C)
Distant galaxies appear to be much younger than nearby galaxies, due to the finite speed of light, and not because the universe is expanding. Distances within the Milky Way remain constant, due to gravitational interactions. However, distant galaxies are receding faster than nearby galaxies, as described by Hubble's law, which demonstrates that space (between all galaxies) is expanding.
Student responses
Section 4136
(A) : 1 student
(B) : 4 students
(C) : 14 students
(D) : 10 students
Student responses
Section 5076
(A) : 2 students
(B) : 7 students
(C) : 10 students
(D) : 4 students
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q12.2
Students were asked the following clicker question (Classroom Performance System, einstruction.com) at the start of their learning cycle:
[0.3 points.] How do we know that the universe is expanding?
(A) The distance from the Sun to the Earth is increasing.
(B) The speed of light is slowing down.
(C) Distant galaxies appear to be moving away faster than nearby galaxies.
(D) Distant galaxies appear to be much younger than nearby galaxies.
Correct answer: (C)
Distant galaxies appear to be much younger than nearby galaxies, due to the finite speed of light, and not because the universe is expanding. Distances within the Milky Way remain constant, due to gravitational interactions. However, distant galaxies are receding faster than nearby galaxies, as described by Hubble's law, which demonstrates that space (between all galaxies) is expanding.
Student responses
Section 4136
(A) : 1 student
(B) : 4 students
(C) : 14 students
(D) : 10 students
Student responses
Section 5076
(A) : 2 students
(B) : 7 students
(C) : 10 students
(D) : 4 students
20070515
Physics quiz question: sub-zero ice versus super-zero water
Physics 8A Quiz 11, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Physics 8A learning goal Q11.2
[3.0 points.] Consider an ice cube of unknown mass that is taken from a freezer, where the cube's temperature was –5.00 degrees C, and dropped into an insulated container of water (mass unknown) at +5.00 degrees C. Assume that no heat was transferred to/from the contents of the container while its contents reach an equilibrium state. c_ice = 2,100 J/(kg*K). c_water = 4,186 J/(kg*K). L_fusion/melting = 334,000 J/kg.
(Cf. Young and Freeman, University Physics, 11/e, Problem 17.101(a).)
[Version 1]
Which one of the following choices best describes the initial mass of –5.00 degrees C ice, compared to the initial mass of +5.00 degrees C water, if the final equilibrium state is entirely water at 0 degrees C?
(A) m_ice < m_water.
(B) m_ice = m_water.
(C) m_ice > m_water.
(D) (Not enough information is given to determine the relative mass of ice and water in the initial state of the system.)
Correct answer: (A)
To warm up from -5.00 degrees C to 0 degrees C, 10,500 J of heat must be added per kg of ice. To cool down from +5.00 degrees C to 0 degrees C, 20,930 J of heat must be removed per kg of water. Thus m_ice = m_water, then the final state would be a mixture of ice and water at 0 degrees C. Since the final state is all water at 0 degrees C, then 334,000 J of heat must have been added per kg of ice to melt it, and thus m_ice < m_water.
Student responses:
(A) : 3 students
(B) : 3 students
(C) : 9 students
(D) : 0 students
[Version 2]
Which one of the following choices best describes the initial mass of –5.00 degrees C ice, compared to the initial mass of +5.00 degrees C water, if the final equilibrium state is entirely ice at 0 degrees C?
(A) m_ice < m_water.
(B) m_ice = m_water.
(C) m_ice > m_water.
(D) (Not enough information is given to determine the relative mass of ice and water in the initial state of the system.)
Correct answer: (C)
To warm up from -5.00 degrees C to 0 degrees C, 10,500 J of heat must be added per kg of ice. To cool down from +5.00 degrees C to 0 degrees C, 20,930 J of heat must be removed per kg of water. Thus m_ice = m_water, then the final state would be a mixture of ice and water at 0 degrees C. Since the final state is all ice at 0 degrees C, then 334,000 J of heat must have been removed per kg of water to freeze it, and thus m_ice > m_water.
Student responses:
(A) : 2 students
(B) : 1 student
(C) : 10 students
(D) : 0 students
Another one of those questions with two different versions with non-complementary distribution of responses...
Cuesta College, San Luis Obispo, CA
Physics 8A learning goal Q11.2
[3.0 points.] Consider an ice cube of unknown mass that is taken from a freezer, where the cube's temperature was –5.00 degrees C, and dropped into an insulated container of water (mass unknown) at +5.00 degrees C. Assume that no heat was transferred to/from the contents of the container while its contents reach an equilibrium state. c_ice = 2,100 J/(kg*K). c_water = 4,186 J/(kg*K). L_fusion/melting = 334,000 J/kg.
(Cf. Young and Freeman, University Physics, 11/e, Problem 17.101(a).)
[Version 1]
Which one of the following choices best describes the initial mass of –5.00 degrees C ice, compared to the initial mass of +5.00 degrees C water, if the final equilibrium state is entirely water at 0 degrees C?
(A) m_ice < m_water.
(B) m_ice = m_water.
(C) m_ice > m_water.
(D) (Not enough information is given to determine the relative mass of ice and water in the initial state of the system.)
Correct answer: (A)
To warm up from -5.00 degrees C to 0 degrees C, 10,500 J of heat must be added per kg of ice. To cool down from +5.00 degrees C to 0 degrees C, 20,930 J of heat must be removed per kg of water. Thus m_ice = m_water, then the final state would be a mixture of ice and water at 0 degrees C. Since the final state is all water at 0 degrees C, then 334,000 J of heat must have been added per kg of ice to melt it, and thus m_ice < m_water.
Student responses:
(A) : 3 students
(B) : 3 students
(C) : 9 students
(D) : 0 students
[Version 2]
Which one of the following choices best describes the initial mass of –5.00 degrees C ice, compared to the initial mass of +5.00 degrees C water, if the final equilibrium state is entirely ice at 0 degrees C?
(A) m_ice < m_water.
(B) m_ice = m_water.
(C) m_ice > m_water.
(D) (Not enough information is given to determine the relative mass of ice and water in the initial state of the system.)
Correct answer: (C)
To warm up from -5.00 degrees C to 0 degrees C, 10,500 J of heat must be added per kg of ice. To cool down from +5.00 degrees C to 0 degrees C, 20,930 J of heat must be removed per kg of water. Thus m_ice = m_water, then the final state would be a mixture of ice and water at 0 degrees C. Since the final state is all ice at 0 degrees C, then 334,000 J of heat must have been removed per kg of water to freeze it, and thus m_ice > m_water.
Student responses:
(A) : 2 students
(B) : 1 student
(C) : 10 students
(D) : 0 students
Another one of those questions with two different versions with non-complementary distribution of responses...
20070514
Astronomy clicker question: metal-rich stars
Astronomy 10, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q11.5
Students were asked the following clicker question (Classroom Performance System, einstruction.com) at the start of their learning cycle:
[0.3 points.] Which type of stars is more abundant in "metals" (elements heavier than hydrogen and helium) in their outermost layers?
(A) Extremely old stars that formed a long time ago.
(B) Young stars that formed very recently.
(C) (Both (A) and (B) would have equal amounts of elements heavier than hydrogen and helium in their outer layers.)
(D) (Neither (A) nor (B), as there cannot be elements heavier than hydrogen and helium in the outer layers of stars.)
Correct answer: (B).
Extremely old stars that formed a long time ago would have mainly hydrogen in their outer layers (while their cores steadily produce metals through its supergiant phase), and after undergoing type II supernova explosions, the metals from the cores of these stars would be incorporated with hydrogen into next generation of younger stars. Thus metals are produced by previous generation stars to be inheirited by the next generation stars.
Student responses
Section 4136
(A) : 8 students
(B) : 10 students
(C) : 8 students
(D) : 9 students
Student responses
Section 5076
(A) : 4 students
(B) : 1 student
(C) : 6 students
(D) : 8 students
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q11.5
Students were asked the following clicker question (Classroom Performance System, einstruction.com) at the start of their learning cycle:
[0.3 points.] Which type of stars is more abundant in "metals" (elements heavier than hydrogen and helium) in their outermost layers?
(A) Extremely old stars that formed a long time ago.
(B) Young stars that formed very recently.
(C) (Both (A) and (B) would have equal amounts of elements heavier than hydrogen and helium in their outer layers.)
(D) (Neither (A) nor (B), as there cannot be elements heavier than hydrogen and helium in the outer layers of stars.)
Correct answer: (B).
Extremely old stars that formed a long time ago would have mainly hydrogen in their outer layers (while their cores steadily produce metals through its supergiant phase), and after undergoing type II supernova explosions, the metals from the cores of these stars would be incorporated with hydrogen into next generation of younger stars. Thus metals are produced by previous generation stars to be inheirited by the next generation stars.
Student responses
Section 4136
(A) : 8 students
(B) : 10 students
(C) : 8 students
(D) : 9 students
Student responses
Section 5076
(A) : 4 students
(B) : 1 student
(C) : 6 students
(D) : 8 students
20070511
Astronomy quiz question: novae and type Ia supernovae
Astronomy 10 Quiz 8, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q10.3
[Version 1]
[3.0 points.] Which one of the following choices best describes a close-pair (mass-exchanging) binary system that can have many cycles of nova explosions?
(A) A massive main sequence star and a red dwarf.
(B) A black hole and a white dwarf.
(C) A supergiant and a white dwarf.
(D) A supergiant and a black hole.
(E) Two red dwarfs.
Correct answer: (C)
The hydrogen shed from a supergiant will form a degenerate layer around a white dwarf companion, and this outer layer will undergo fusion, producing a nova explosion.
Student responses
Section 4136
(A) : 6 students
(B) : 0 students
(C) : 26 students
(D) : 1 student
(E) : 0 students
[Version 2]
[3.0 points.] Which one of the following choices best describes a close-pair (mass-exchanging) binary system that can have a type Ia supernova explosion?
(A) A massive main sequence star and a red dwarf.
(B) A black hole and a white dwarf.
(C) A supergiant and a white dwarf.
(D) A supergiant and a black hole.
(E) Two red dwarfs.
Correct answer: (C)
When the hydrogen shed from a supergiant quickly forms a thick degenerate layer around a white dwarf companion (or the alternate theory is that this transfer has been going on for prolonged time over many nova explosion cycles), then the entire white dwarf will undergo fusion, producing a type Ia supernova explosion.
Student responses
Section 5076
(A) : 0 students
(B) : 2 students
(C) : 15 students
(D) : 1 student
(E) : 0 students
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q10.3
[Version 1]
[3.0 points.] Which one of the following choices best describes a close-pair (mass-exchanging) binary system that can have many cycles of nova explosions?
(A) A massive main sequence star and a red dwarf.
(B) A black hole and a white dwarf.
(C) A supergiant and a white dwarf.
(D) A supergiant and a black hole.
(E) Two red dwarfs.
Correct answer: (C)
The hydrogen shed from a supergiant will form a degenerate layer around a white dwarf companion, and this outer layer will undergo fusion, producing a nova explosion.
Student responses
Section 4136
(A) : 6 students
(B) : 0 students
(C) : 26 students
(D) : 1 student
(E) : 0 students
[Version 2]
[3.0 points.] Which one of the following choices best describes a close-pair (mass-exchanging) binary system that can have a type Ia supernova explosion?
(A) A massive main sequence star and a red dwarf.
(B) A black hole and a white dwarf.
(C) A supergiant and a white dwarf.
(D) A supergiant and a black hole.
(E) Two red dwarfs.
Correct answer: (C)
When the hydrogen shed from a supergiant quickly forms a thick degenerate layer around a white dwarf companion (or the alternate theory is that this transfer has been going on for prolonged time over many nova explosion cycles), then the entire white dwarf will undergo fusion, producing a type Ia supernova explosion.
Student responses
Section 5076
(A) : 0 students
(B) : 2 students
(C) : 15 students
(D) : 1 student
(E) : 0 students
20070510
Physics quiz question: ideal fluid flow through horizontal pipe
Physics 8A (currently Physics 208A) Quiz 10, spring semester 2007
Cuesta College, San Luis Obispo, CA
Cf. Young and Freeman, University Physics, 11/e, Exercise 14.40
Water enters a horizontal section of pipe at a rate of 1.80 m3/s at point [1], where the radius is 0.300 m, and the pressure is 2.50×105 Pa. Assume ideal fluid flow.
At a point [2] further along the pipe, the pressure is less than at point [1]. The radius r2 of the pipe at point [2] is __________ compared to the radius r1 point [1].
(A) smaller.
(B) the same.
(C) larger.
(D) (Not enough information given.)
Correct answer (highlight to unhide): (A)
Writing out Bernoulli's equation:
0 = ∆P + ρ·g·∆y + (1/2)·ρ·∆(v2),
the decrease in pressure as the water flows from [1]→[2] means that the first term ∆P is negative, and the second term ρ·g·∆y is zero because there is no change in elevation y. For the equality to hold, the third term (1/2)·ρ·∆(v2) must then be positive, such that:
0 < (1/2)·ρ·∆(v2),
0 < ∆(v2),
0 < v22 - v12,
v12 < v22,
v1 < v2.
From the continuity equation (conservation of fluid flow):
A1·v1 = A2·v2,
since v1 < v2, then A1 > A2, and thus r1 > r2 (the pipe is smaller at point [2] than at point [1]).
Student responses:
(A) : 9 students
(B) : 0 students
(C) : 5 students
(D) : 0 students
Cuesta College, San Luis Obispo, CA
Cf. Young and Freeman, University Physics, 11/e, Exercise 14.40
Water enters a horizontal section of pipe at a rate of 1.80 m3/s at point [1], where the radius is 0.300 m, and the pressure is 2.50×105 Pa. Assume ideal fluid flow.
At a point [2] further along the pipe, the pressure is less than at point [1]. The radius r2 of the pipe at point [2] is __________ compared to the radius r1 point [1].
(A) smaller.
(B) the same.
(C) larger.
(D) (Not enough information given.)
Correct answer (highlight to unhide): (A)
Writing out Bernoulli's equation:
0 = ∆P + ρ·g·∆y + (1/2)·ρ·∆(v2),
the decrease in pressure as the water flows from [1]→[2] means that the first term ∆P is negative, and the second term ρ·g·∆y is zero because there is no change in elevation y. For the equality to hold, the third term (1/2)·ρ·∆(v2) must then be positive, such that:
0 < (1/2)·ρ·∆(v2),
0 < ∆(v2),
0 < v22 - v12,
v12 < v22,
v1 < v2.
From the continuity equation (conservation of fluid flow):
A1·v1 = A2·v2,
since v1 < v2, then A1 > A2, and thus r1 > r2 (the pipe is smaller at point [2] than at point [1]).
Student responses:
(A) : 9 students
(B) : 0 students
(C) : 5 students
(D) : 0 students
20070509
Physics quiz question: kilogram cube of aluminum
Physics 8A Quiz 10, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Physics 8A learning goal Q10.1
[3.0 points.] Which one of the following choices best corresponds to the side of a 1.00 kg cube of aluminum? (The density of aluminum is 2.70x10^3 kg/m3.)
(A) 0.0140 m.
(B) 0.0192 m.
(C) 0.0446 m.
(D) 0.0718 m
(Cf. Young and Freeman, University Physics, 11/e, Exercise 14.4.)
Correct answer: (D)
Density (rho) = mass/volume = m/(d^3), where d is a side of the cube. Then d = (m/rho)^(1/3). The incorrect response (C) is the radius of a 1.00 kg sphere of aluminum!
Student responses:
(A) : 1 student
(B) : 3 students
(C) : 7 students
(D) : 17 students
Cuesta College, San Luis Obispo, CA
Physics 8A learning goal Q10.1
[3.0 points.] Which one of the following choices best corresponds to the side of a 1.00 kg cube of aluminum? (The density of aluminum is 2.70x10^3 kg/m3.)
(A) 0.0140 m.
(B) 0.0192 m.
(C) 0.0446 m.
(D) 0.0718 m
(Cf. Young and Freeman, University Physics, 11/e, Exercise 14.4.)
Correct answer: (D)
Density (rho) = mass/volume = m/(d^3), where d is a side of the cube. Then d = (m/rho)^(1/3). The incorrect response (C) is the radius of a 1.00 kg sphere of aluminum!
Student responses:
(A) : 1 student
(B) : 3 students
(C) : 7 students
(D) : 17 students
20070508
Astronomy midterm question: comparing stars using blackbody radiation laws
Astronomy 10 Midterm 3, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q8.3
[Version 1]
[15 points.] Consider the following statement: "If two stars have the same brightness, the star with the lower temperature will be bigger." Discuss whether this statement is true or not, and support your answer using Wien's law and/or the Stefan-Boltzmann law.
Solution and grading rubric:
Grading distribution:
Section 4136
p: 21 students
r: 2 students
t: 7 students
v: 7 students
x: 2 students
y: 0 students
z: 0 students
[Version 2]
[15 points.] Consider the following statement: "If two stars have the same color, the brighter star will be bigger." Discuss whether this statement is true or not, and support your answer using Wien's law and/or the Stefan-Boltzmann law.
Solution and grading rubric:
Grading distribution:
Section 5076
p: 7 students
r: 3 students
t: 6 students
v: 4 students
x: 0 students
y: 0 students
z: 0 students
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q8.3
[Version 1]
[15 points.] Consider the following statement: "If two stars have the same brightness, the star with the lower temperature will be bigger." Discuss whether this statement is true or not, and support your answer using Wien's law and/or the Stefan-Boltzmann law.
Solution and grading rubric:
- p = 15/15: Correct.
Wien's law: peak wavelength is inversely proportional to temperature, size is not a factor. The Stefan-Boltzmann law: luminosity (brightness) proportional to size * (Temperature)^4, such that two stars can have the same brightness if the smaller star were hotter, and the larger star were cooler. - r = 12/15:
Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. - t = 9/15:
Contains right ideas, but discussion is unclear/incomplete or contains major errors. At least recognizes that the Stefan-Boltzmann law is applicable, but argument is garbled. - v = 6/15:
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. - x = 3/15:
Implementation/application of ideas, but credit given for effort rather than merit. Agrees or disagrees with statement with no discussion. - y = 1.5/15:
Irrelevant discussion/effectively blank. - z = 0/15:
Blank.
Grading distribution:
Section 4136
p: 21 students
r: 2 students
t: 7 students
v: 7 students
x: 2 students
y: 0 students
z: 0 students
[Version 2]
[15 points.] Consider the following statement: "If two stars have the same color, the brighter star will be bigger." Discuss whether this statement is true or not, and support your answer using Wien's law and/or the Stefan-Boltzmann law.
Solution and grading rubric:
- p = 15/15:
Correct. Wien's law: temperature is inverserly proportional to peak wavelength, which is related to color. Since both stars have the same color, then they must have the same temperature. The Stefan-Boltzmann law: luminosity
(brightness) proportional to size * (Temperature)^4, such that the smaller star must be dimmer, and the larger star must be cooler, given that they are the same size. - r = 12/15:
Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. Uses the Stefan-Boltmann law correctly, but the temperature is assumed to be the same (or implied), not explicitly derived from applying Wien's law. - t = 9/15:
Contains right ideas, but discussion is unclear/incomplete or contains major errors. At least recognizes how the Stefan-Boltzmann law and Wien's law are applicable, but argument is garbled. - v = 6/15:
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. - x = 3/15:
Implementation/application of ideas, but credit given for effort rather than merit. Agrees or disagrees with statement with no discussion. - y = 1.5/15:
Irrelevant discussion/effectively blank. - z = 0/15:
Blank.
Grading distribution:
Section 5076
p: 7 students
r: 3 students
t: 6 students
v: 4 students
x: 0 students
y: 0 students
z: 0 students
20070507
Astronomy current events question: Gliese 581's super earth, part 2
Astronomy 10L, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Students are assigned to read online articles on current astronomy events (skytonight.com, from Sky & Telescope magazine), 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!)
[0.2 points.] How was the recently discovered planet orbiting the red dwarf star Gliese 581 discovered? Circle your answer below.
(A) From the repetitive wobbles that the planet gravitationally exerts on Gliese 581.
(B) From the amount of light blocked by the planet as it passes in front of Gliese 581.
(C) From the amount of bright light emitted by the very hot planet, compared to the dim cool light emitted from Gliese 581.
(D) From deciphering ancient hieroglyphics in a newly discovered tomb in Egypt.
(E) From deciphering ancient glyphs from a previously overlooked Mayan codex.
Correct answer: (A).
Student responses
Section 4137
(A) : 13 students
(B) : 3 students
(C) : 5 students
(D) : 1 student
(E) : 0 students
Section 4138
(A) : 11 students
(B) : 5 students
(C) : 3 students
(D) : 0 students
(E) : 0 students
Section 4139
(A) : 10 students
(B) : 6 students
(C) : 1 student
(D) : 0 students
(E) : 0 students
Note that choices (A)-(C) are all used to find extrasolar planets. The one student who picked the nonsense choice (D) admitted to selecting it blindly at random.
Cuesta College, San Luis Obispo, CA
Students are assigned to read online articles on current astronomy events (skytonight.com, from Sky & Telescope magazine), 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!)
[0.2 points.] How was the recently discovered planet orbiting the red dwarf star Gliese 581 discovered? Circle your answer below.
(A) From the repetitive wobbles that the planet gravitationally exerts on Gliese 581.
(B) From the amount of light blocked by the planet as it passes in front of Gliese 581.
(C) From the amount of bright light emitted by the very hot planet, compared to the dim cool light emitted from Gliese 581.
(D) From deciphering ancient hieroglyphics in a newly discovered tomb in Egypt.
(E) From deciphering ancient glyphs from a previously overlooked Mayan codex.
Correct answer: (A).
Student responses
Section 4137
(A) : 13 students
(B) : 3 students
(C) : 5 students
(D) : 1 student
(E) : 0 students
Section 4138
(A) : 11 students
(B) : 5 students
(C) : 3 students
(D) : 0 students
(E) : 0 students
Section 4139
(A) : 10 students
(B) : 6 students
(C) : 1 student
(D) : 0 students
(E) : 0 students
Note that choices (A)-(C) are all used to find extrasolar planets. The one student who picked the nonsense choice (D) admitted to selecting it blindly at random.
20070504
Astronomy current events question: Gliese 581's super earth, part 1
Astronomy 10L, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Students are assigned to read online articles on current astronomy events (skytonight.com, from Sky & Telescope magazine), 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!)
[0.2 points.] What is most significant about the recently discovered planet orbiting the red dwarf star Gliese 581? Circle your answer below.
(A) It is about to burned up by Gliese 581, as it is so close that its orbit around it is already only 13 days long.
(B) It is about to be swallowed up by Gliese 581 as the red dwarf becomes a giant.
(C) It may be an extremely old Earth-like planet, and thus may harbor an advanced technological civilization.
(D) It may be an Earth-like planet in its first stages of formation, with the correct conditions for carbon-based life.
(E) It may be an Earth-like planet at the right distance to have water in liquid form.
Correct answer: (E).
Student responses
Section 4137
(A) : 0 students
(B) : 0 students
(C) : 1 student
(D) : 1 student
(E) : 17 students
Section 4138
(A) : 1 student
(B) : 1 student
(C) : 1 student
(D) : 3 students
(E) : 13 students
Section 4139
(A) : 1 student
(B) : 0 students
(C) : 0 students
(D) : 2 students
(E) : 14 students
Cuesta College, San Luis Obispo, CA
Students are assigned to read online articles on current astronomy events (skytonight.com, from Sky & Telescope magazine), 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!)
[0.2 points.] What is most significant about the recently discovered planet orbiting the red dwarf star Gliese 581? Circle your answer below.
(A) It is about to burned up by Gliese 581, as it is so close that its orbit around it is already only 13 days long.
(B) It is about to be swallowed up by Gliese 581 as the red dwarf becomes a giant.
(C) It may be an extremely old Earth-like planet, and thus may harbor an advanced technological civilization.
(D) It may be an Earth-like planet in its first stages of formation, with the correct conditions for carbon-based life.
(E) It may be an Earth-like planet at the right distance to have water in liquid form.
Correct answer: (E).
Student responses
Section 4137
(A) : 0 students
(B) : 0 students
(C) : 1 student
(D) : 1 student
(E) : 17 students
Section 4138
(A) : 1 student
(B) : 1 student
(C) : 1 student
(D) : 3 students
(E) : 13 students
Section 4139
(A) : 1 student
(B) : 0 students
(C) : 0 students
(D) : 2 students
(E) : 14 students
20070503
Physics midterm question: two-box system, frictionless table, ideal pulley (revisited)
Physics 8A Midterm 3, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Physics 8A learning goal Q7.2
[3.0 points.] Consider a box of unknown mass on a frictionless table, connected by an ideal cable to a 1.08 kg box. The pulley has negligible mass, and is frictionless. The system is released from rest, and after the 1.08 kg box has moved 0.750 m, it has a speed of 1.55 m/s. Neglect air resistance.
Which one of the following choices best corresponds to the mass of the unknown box?
(A) 3.83 kg.
(B) 4.04 kg.
(C) 5.53 kg.
(D) 6.61 kg.
(Cf. Young and Freeman, University Physics, 11/e, Problem 6.82.)
Correct answer: (C)
The decrease in gravitational potential energy of the 1.08 kg box is equal to the sum of the increases in kinetic energies of the 1.08 kg box and the unknown mass box. Thus if y_f = 0, then:
m_unknown = 2*(1.08 kg)*g*y_i)/((v_f)^2) - 1.08 kg = 5.53 kg.
Student responses:
(A) : 5 students
(B) : 4 students
(C) : 16 students
(D) : 8 students
Cf. Physics quiz question: two-box system, frictionless table, ideal pulley (20070405)
Cuesta College, San Luis Obispo, CA
Physics 8A learning goal Q7.2
[3.0 points.] Consider a box of unknown mass on a frictionless table, connected by an ideal cable to a 1.08 kg box. The pulley has negligible mass, and is frictionless. The system is released from rest, and after the 1.08 kg box has moved 0.750 m, it has a speed of 1.55 m/s. Neglect air resistance.Which one of the following choices best corresponds to the mass of the unknown box?
(A) 3.83 kg.
(B) 4.04 kg.
(C) 5.53 kg.
(D) 6.61 kg.
(Cf. Young and Freeman, University Physics, 11/e, Problem 6.82.)
Correct answer: (C)
The decrease in gravitational potential energy of the 1.08 kg box is equal to the sum of the increases in kinetic energies of the 1.08 kg box and the unknown mass box. Thus if y_f = 0, then:
m_unknown = 2*(1.08 kg)*g*y_i)/((v_f)^2) - 1.08 kg = 5.53 kg.
Student responses:
(A) : 5 students
(B) : 4 students
(C) : 16 students
(D) : 8 students
Cf. Physics quiz question: two-box system, frictionless table, ideal pulley (20070405)
20070502
Physics midterm question: rim-axis ring
Physics 8A Midterm 3, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Physics 8A learning goal Q9.3
[3.0 points.] A thin ring of mass M and radius R rotates about an axis perpendicular to the ring's plane, through its rim. Which one of the following choices best describes the moment of inertia about this rim axis?
(A) (1/2)*M*R^2.
(B) M*R^2.
(C) (3/2)*M*R^2.
(D) 2*M*R^2.
(Cf. Young and Freeman, University Physics, 11/e, Exercise 9.52.)
Correct answer: (D)
The parallel-axis theorem is used to relate the moment of inertia about a point on its rim (I_parallel) with the moment of inertia of the ring (I_ring) about its own center of mass:
I_parallel = I_ring + M*d^2,
where I_ring = M*R*^2, and d = R, thus I_parallel = 2*M*R^2.
Student responses:
(A) : 2 students
(B) : 8 students
(C) : 3 students
(D) : 20 students
Cuesta College, San Luis Obispo, CA
Physics 8A learning goal Q9.3
[3.0 points.] A thin ring of mass M and radius R rotates about an axis perpendicular to the ring's plane, through its rim. Which one of the following choices best describes the moment of inertia about this rim axis?(A) (1/2)*M*R^2.
(B) M*R^2.
(C) (3/2)*M*R^2.
(D) 2*M*R^2.
(Cf. Young and Freeman, University Physics, 11/e, Exercise 9.52.)
Correct answer: (D)
The parallel-axis theorem is used to relate the moment of inertia about a point on its rim (I_parallel) with the moment of inertia of the ring (I_ring) about its own center of mass:
I_parallel = I_ring + M*d^2,
where I_ring = M*R*^2, and d = R, thus I_parallel = 2*M*R^2.
Student responses:
(A) : 2 students
(B) : 8 students
(C) : 3 students
(D) : 20 students
20070501
Physics midterm question: bounce or splat impulse?
Physics 8A Midterm 3, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Physics 8A learning goal Q8.1
[10 points.] A gun is fired straight down at a steel plate. Is the impulse on the plate from a single bullet impact greater if the bullet bounces off of the plate, or if the bullet squashes and sticks to the plate, or is the impulse the same in either case? Explain your answer using properties of impulse and momentum.
(Cf. Young and Freeman, University Physics, 11/e, Discussion Question 8.13.)
Solution and grading rubric:
Grading distribution:
p: 2 students
r: 7 students
t: 16 students
v: 8 students
x: 0 students
y: 0 students
z: 0 students
A sample (incorrect) student response (from J. H.) is shown below. At least some attempt was made to relate this question to a real-life experience. This was graded as a "t" category response.
Cuesta College, San Luis Obispo, CA
Physics 8A learning goal Q8.1
[10 points.] A gun is fired straight down at a steel plate. Is the impulse on the plate from a single bullet impact greater if the bullet bounces off of the plate, or if the bullet squashes and sticks to the plate, or is the impulse the same in either case? Explain your answer using properties of impulse and momentum.
(Cf. Young and Freeman, University Physics, 11/e, Discussion Question 8.13.)
Solution and grading rubric:
- p = 10/10: Correct.
Impulse is equal to delta(p), where p_i is down, and p_f is either zero (stuck to plate), or up (bounces up off plate). Respectively then the impulse on the plate is then equal to -p_i or -2*p_i (if the collision is elastic), thus the impulse on the plate is greater when the bullet bounces off the plate. This is irregardless of the time of the impact. - r = 8/10:
As (p), but argument indirectly, weakly, or only by definition supports the statement to be proven, or has minor inconsistencies or loopholes. Utilizes impulse = delta(p) relation with understanding of initial and final momentum directions, but argument is garbled or contradicts correct set-up. - t = 6/10:
Nearly correct, but argument has conceptual errors, or is incomplete. Some attempt at incorporating impulse and momentum in discussion. - v = 4/10:
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Discussion based on energy or angular momentum considerations, or a choice that has no explanation. - x = 2/10:
Implementation/application of ideas, but credit given for effort rather than merit. - y = 1/10:
Irrelevant discussion/effectively blank. - z = 0/10:
Blank.
Grading distribution:
p: 2 students
r: 7 students
t: 16 students
v: 8 students
x: 0 students
y: 0 students
z: 0 students
A sample (incorrect) student response (from J. H.) is shown below. At least some attempt was made to relate this question to a real-life experience. This was graded as a "t" category response.
