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
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
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
20070430
Physics midterm problem: rolling uphill, with friction
Physics 8A Midterm 3, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Physics 8A learning goal Q9.2
[20 points.] A 7.00 kg bowling ball of radius 0.150 m rolls up an inclined plane. When a Physics 8A student releases the bowling ball at the bottom of the inclined plane, it has an initial speed of 4.00 m/s. Assume that the bowling ball rolls up the inclined plane without slipping, and that work done by friction and air resistance against the bowling ball removes one-tenth of its initial energy by the time it reaches its maximum vertical height above the bottom of the inclined plane. Find the maximum vertical height increase of the bowling ball above the bottom of the inclined plane. Show your work and explain your reasoning.
(Cf. Young and Freeman, University Physics, 11/e, Problem 10.81.)
Solution and grading rubric:
Grading distribution:
p: 3 students
r: 3 students
t: 12 students
v: 12 students
x: 2 students
y: 0 students
z: 0 students
Cuesta College, San Luis Obispo, CA
Physics 8A learning goal Q9.2
[20 points.] A 7.00 kg bowling ball of radius 0.150 m rolls up an inclined plane. When a Physics 8A student releases the bowling ball at the bottom of the inclined plane, it has an initial speed of 4.00 m/s. Assume that the bowling ball rolls up the inclined plane without slipping, and that work done by friction and air resistance against the bowling ball removes one-tenth of its initial energy by the time it reaches its maximum vertical height above the bottom of the inclined plane. Find the maximum vertical height increase of the bowling ball above the bottom of the inclined plane. Show your work and explain your reasoning.
(Cf. Young and Freeman, University Physics, 11/e, Problem 10.81.)
Solution and grading rubric:
- p = 20/20: Correct.
The intial total mechanical energy is K_rot + K_trans =78.4 J. One-tenth of this energy is lost to friction, so the open-energy
equation is
-(1/10)*(78.4 J) = (1/2)*(I_sphere)*(0 - w_i^2) + (1/2)*m*(0 -v_i^2) + m*g*(y_f - 0),
where w_i = v_i/r, thus y_f = 1.03 m. Or more simply, nine-tenths of 78.4 J is converted to U_grav, so m*g*y_f = (9/10)*(78.4 J). - r = 16/20:
Nearly correct, but includes minor math errors. - t = 12/20:
Nearly correct, but approach has conceptual errors, and/or major/compounded math errors. Omits K_rot (but still has frictional losses), or includes both K_trans and K_rot, but does not account for frictional losses. - v = 8/20:
Implementation of right ideas, but in an inconsistent, incomplete, or unorganized manner. At least attempts (open) energy conservation. - x = 4/20:
Implementation of ideas, but credit given for effort rather than merit. - y = 2/20:
Irrelevant discussion/effectively blank. - z = 0/20:
Blank.
Grading distribution:
p: 3 students
r: 3 students
t: 12 students
v: 12 students
x: 2 students
y: 0 students
z: 0 students
20070425
Astronomy clicker question: main sequence to giant/supergiant evolution
Astronomy 10, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal M3.1
Students were asked the following clicker question (Classroom Performance System, einstruction.com) in the middle of their learning cycle:
[0.3 points.] According to the Stefan-Boltzmann law, how does the luminosity of a medium mass or massive main sequence star change as its outer layers expand and cool off, as it becomes a giant or supergiant?
(A) It becomes dimmer.
(B) It remains the same.
(C) It becomes brighter.
(D) (Any of the above (A)-(C) choices, depending on how old the star is.)
Correct answer: (B).
The evolutionary track of a main sequence star as it becomes a giant or supergiant can be approximated as a horizontal path from left-to-right across an H-R diagram, which means that its luminosity remains constant while its surface temperature decreases. From the Stefan-Boltzmann law, constant luminosity means that size must increase while temperature decreases.
Student responses
Section 4136
(A) : 13 students
(B) : 3 students
(C) : 9 students
(D) : 5 students
Section 5076
(A) : 8 students
(B) : 6 students
(C) : 4 students
(D) : 2 students
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal M3.1
Students were asked the following clicker question (Classroom Performance System, einstruction.com) in the middle of their learning cycle:
[0.3 points.] According to the Stefan-Boltzmann law, how does the luminosity of a medium mass or massive main sequence star change as its outer layers expand and cool off, as it becomes a giant or supergiant?
(A) It becomes dimmer.
(B) It remains the same.
(C) It becomes brighter.
(D) (Any of the above (A)-(C) choices, depending on how old the star is.)
Correct answer: (B).
The evolutionary track of a main sequence star as it becomes a giant or supergiant can be approximated as a horizontal path from left-to-right across an H-R diagram, which means that its luminosity remains constant while its surface temperature decreases. From the Stefan-Boltzmann law, constant luminosity means that size must increase while temperature decreases.
Student responses
Section 4136
(A) : 13 students
(B) : 3 students
(C) : 9 students
(D) : 5 students
Section 5076
(A) : 8 students
(B) : 6 students
(C) : 4 students
(D) : 2 students
20070424
Astronomy quiz question: CNO cycle stars
Astronomy 10 Quiz 9, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q9.4
[3.0 points.] Which one of the following choices best explains what allows hydrogen to fuse together with much heavier elements in the cores of massive main sequence stars?
(A) Stronger gravitational forces.
(B) Stronger degenerate pressures.
(C) Continuous absorption and reemission of higher energy photons.
(D) Higher temperatures.
(E) Stronger convection currents.
Correct answer: (D)
Higher temperatures mean faster speeds. For hydrogen fusion, the temperature must be high enough for protons to approach close enough to fuse, in spite of the mutually repulsive force due to their positive charge. For hydrogen to fuse together with a heavier element (such as carbon, which has 14 protons), the temperature must be even higher for the hydrogen proton to approach the stronger repelling carbon nucleus.
Student responses
Section 4136
(A) : 18 students
(B) : 6 students
(C) : 3 students
(D) : 2 students
(E) : 10 students
Student responses
Section 5076
(A) : 5 student
(B) : 2 students
(C) : 3 students
(D) : 10 students
(E) : 1 students
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q9.4
[3.0 points.] Which one of the following choices best explains what allows hydrogen to fuse together with much heavier elements in the cores of massive main sequence stars?
(A) Stronger gravitational forces.
(B) Stronger degenerate pressures.
(C) Continuous absorption and reemission of higher energy photons.
(D) Higher temperatures.
(E) Stronger convection currents.
Correct answer: (D)
Higher temperatures mean faster speeds. For hydrogen fusion, the temperature must be high enough for protons to approach close enough to fuse, in spite of the mutually repulsive force due to their positive charge. For hydrogen to fuse together with a heavier element (such as carbon, which has 14 protons), the temperature must be even higher for the hydrogen proton to approach the stronger repelling carbon nucleus.
Student responses
Section 4136
(A) : 18 students
(B) : 6 students
(C) : 3 students
(D) : 2 students
(E) : 10 students
Student responses
Section 5076
(A) : 5 student
(B) : 2 students
(C) : 3 students
(D) : 10 students
(E) : 1 students
20070420
Bon mots: understanding trumps math
"I love only nature, and I hate mathematicians."
--Richard Feynman
"Nothing in life is to be feared. It is only to be understood."
--Marie Curie
Upon seeing the first quote in the class announcements, a student asked who Richard Feynmann was, although it was not clear whether this interest was due to a pro-nature or anti-math sentiment.
--Richard Feynman
"Nothing in life is to be feared. It is only to be understood."
--Marie Curie
Upon seeing the first quote in the class announcements, a student asked who Richard Feynmann was, although it was not clear whether this interest was due to a pro-nature or anti-math sentiment.
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