Physics quiz archive: temperature, thermal equilibrium, heat transfers

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


Sections 70854, 70855 results

0- 6 :
7-12 :	******* [low = 9]
13-18 :	*************
19-24 :	******************* [mean = 18.9 +/- 5.4]
25-30 :	*** [high = 27]

Astronomy quiz archive: Milky Way, nucleosynthesis, cosmology

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

Section 70158, version 1
Exam code: quiz07Sl0p


Section 70158

0- 8.0 :
8.5-16.0 :	******** [low = 9.5]
16.5-24.0 :	******************* [mean = 23.0 +/- 7.2]
24.5-32.0 :	**********
32.5-40.0 :	****** [high = 36.5]

Section 70160, version 1
Exam code: quiz07ni4N


Section 70160

0- 8.0 :
8.5-16.0 :	****** [low = 10.0]
16.5-24.0 :	********* [mean = 23.3 +/- 7.1]
24.5-32.0 :	***********
32.5-40.0 :	** [high = 33.0]

Astronomy midterm question: plausible IAU classification of 300163 (2006 VW139) before breaking apart?

Astronomy 210 Midterm 2, fall semester 2017
Cuesta College, San Luis Obispo, CA

An international team of astronomers recently discovered two asteroids with comet-like features orbiting each other in the asteroid belt:

NASA's Hubble Space Telescope helped an international team of astronomers find that an unusual object in the asteroid belt, designated 300163 (2006 VW139), is in fact two asteroids of almost the same mass and size, orbiting each other at a distance of 60 miles. They also have comet-like features, including a bright halo of material, called a coma, and a long tail of dust. Roughly 5,000 years ago, 300163 (2006 VW139) probably broke into these two pieces due to a fast rotation.[*]

Before it broke apart 5,000 years ago, discuss how 300163 (2006 VW139) might have been originally classified, using the International Astronomical Union classification scheme. Clearly state your assumptions about what properties 300163 (2006 VW139) might have had before it broke apart.

[*] J. Agarwal, "Comet or Asteroid? Hubble Discovers that a Unique Object is a Binary," hubblesite.org/news_release/news/2017-32.

Solution and grading rubric:

• p:
  Correct. Discusses IAU classification scheme to argue that before breaking up 5,000 years ago:
  1. 300163 (2006 VW139) was in the asteroid belt, orbiting the sun, and thus could not have been a moon; and not having been able to gravitationally dominate its orbit by clearing asteroids out or pulling in asteroids into itself, could not have have been a planet (assuming that it had a rounded shape); and
  2. depending on whether its shape was irregular or rounded, it would have either been classified as solar system debris or a dwarf planet.
• r:
  Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. May have instead discussed how the two components of 300163 (2006 VW139) today could be categorized in terms of the IAU classification scheme, instead of how it might have been categorized before breaking up 5,000 years ago.
• t:
  Contains right ideas, but discussion is unclear/incomplete or contains major errors. Explicitly lists IAU requirements, but does not apply them correctly/consistently.
• v:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Discussion only tangentially related to the IAU classification scheme.
• x:
  Implementation/application of ideas, but credit given for effort rather than merit. Discussion unrelated to the IAU classification scheme.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.

Grading distribution:
Section 70158
Exam code: midterm02Sm5n
p: 35 students
r: 4 students
t: 5 students
v: 2 students
x: 0 students
y: 0 students
z: 0 students

Section 70160
Exam code: midterm02nJv3
p: 23 students
r: 5 students
t: 3 students
v: 0 students
x: 0 students
y: 0 students
z: 0 students

A sample "p" response (from student 0987):
Another sample "p" response (from student 1796):
A sample "r" response (from student 1881), discussing the current classification of 300163 (2006 VW139) today:

Astronomy midterm question: apparent magnitude dimmer than absolute magnitude?

Astronomy 210 Midterm 2, fall semester 2017
Cuesta College, San Luis Obispo, CA

An astronomy question on an online discussion board[*] was asked:

Qu: If the distance to a star is 20 parsecs, and its absolute magnitude is +5.5, what is its apparent magnitude?
day: The apparent magnitude would be dimmer than +5.5.

Discuss whether this answer is correct or incorrect, and how you know this. Explain using the relationships between apparent magnitude, absolute magnitude, and distance.

[*] answers.yahoo.com/question/index?qid=20100615201717AAZwXu7.

Solution and grading rubric:

• p:
  Correct. Understands difference between apparent magnitude m (brightness as seen from Earth, when placed at their actual distance from Earth) and absolute magnitude (M (brightness as seen from Earth, when placed at the "fair comparison distance" of 10 parsecs away). Discusses how this star with an absolute magnitude value of +5.5 (measured at 10 parsecs) will get dimmer when placed farther away to 20 parsecs, and thus its apparent magnitude will be dimmer than its absolute magnitude of +5.5. Then makes conclusion on correctness of response.
• r:
  Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. As (p), but does not explicitly determine incorrectness of response.
• t:
  Contains right ideas, but discussion is unclear/incomplete or contains major errors. At least discussion demonstrates understanding of relationships between apparent magnitudes, absolute magnitudes, and distances.
• v:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. At least attempts to use relationships between apparent magnitudes, absolute magnitudes, and distances.
• x:
  Implementation/application of ideas, but credit given for effort rather than merit. Discussion based on garbled definitions of, or not based on proper relationships between apparent magnitudes, absolute magnitudes, and distances.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.

Grading distribution:
Section 70158
Exam code: midterm02Sm5n
p: 27 students
r: 7 students
t: 10 students
v: 1 student
x: 1 student
y: 0 students
z: 0 students

A sample "p" response (from student 1027):

Astronomy midterm question: apparent magnitude brighter than absolute magnitude?

Astronomy 210 Midterm 2, fall semester 2017
Cuesta College, San Luis Obispo, CA

An astronomy question on an online discussion board[*] was asked:

Qu: If the distance to a star is 20 parsecs, and its absolute magnitude is +5.5, what is its apparent magnitude?
day: The apparent magnitude would be brighter than +5.5.

Discuss whether this answer is correct or incorrect, and how you know this. Explain using the relationships between apparent magnitude, absolute magnitude, and distance.

[*] answers.yahoo.com/question/index?qid=20100615201717AAZwXu7.

Solution and grading rubric:

• p:
  Correct. Understands difference between apparent magnitude m (brightness as seen from Earth, when placed at their actual distance from Earth) and absolute magnitude (M (brightness as seen from Earth, when placed at the "fair comparison distance" of 10 parsecs away). Discusses how this star with an absolute magnitude value of +5.5 (measured at 10 parsecs) will get dimmer when placed farther away to 20 parsecs, and thus its apparent magnitude will be dimmer than its absolute magnitude of +5.5. Then makes conclusion on incorrectness of response.
• r:
  Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. As (p), but does not explicitly determine incorrectness of response.
• t:
  Contains right ideas, but discussion is unclear/incomplete or contains major errors. At least discussion demonstrates understanding of relationships between apparent magnitudes, absolute magnitudes, and distances.
• v:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. At least attempts to use relationships between apparent magnitudes, absolute magnitudes, and distances.
• x:
  Implementation/application of ideas, but credit given for effort rather than merit. Discussion based on garbled definitions of, or not based on proper relationships between apparent magnitudes, absolute magnitudes, and distances.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.

Grading distribution:
Section 70160
Exam code: midterm02nJv3
p: 24 students
r: 3 students
t: 3 students
v: 1 student
x: 0 students
y: 0 students
z: 0 students

A sample "p" response (from student 7237):

Astronomy midterm question: more luminous star redder than same-size less luminous star?

Astronomy 210 Midterm 2, fall semester 2017
Cuesta College, San Luis Obispo, CA

An astronomy question on an online discussion board[*] was asked and answered:

RC: Star X is more luminous than star Y, but they are the same size. Is star X redder or bluer than star Y?
BrT: Since they have the same size, because star X is more luminous it will be redder.

Discuss why this answer is incorrect, and how you know this. Explain using Wien's law, the Stefan-Boltzmann law and/or an H-R diagram.

[*] answers.yahoo.com/question/index?qid=20110203173510AAHqejO.

Solution and grading rubric:

• p:
  Correct. Uses the Stefan-Boltzmann law and/or interprets H-R diagram to demonstrate that in order for two stars to have the same size, the more luminous star X must be hotter than the less luminous star Y, and from Wien's law "redder" corresponds to cooler temperatures, and thus star X cannot be redder than star Y.
• r:
  Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors.
• t:
  Contains right ideas, but discussion is unclear/incomplete or contains major errors.
• v:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. At least attempts to use Wien's law, the Stefan-Boltzmann law, and/or H-R diagram.
• x:
  Implementation/application of ideas, but credit given for effort rather than merit. Discussion not clearly based on Wien's law, the Stefan-Boltzmann law, and/or H-R diagram.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.

Grading distribution:
Section 70158
Exam code: midterm02Sm5n
p: 29 students
r: 5 students
t: 9 students
v: 3 students
x: 0 students
y: 0 students
z: 0 students

Section 70160
Exam code: midterm02nJv3
p: 24 students
r: 2 students
t: 5 students
v: 0 students
x: 0 students
y: 0 students
z: 0 students

A sample "p" response (from student 8622), using a graphical "box method" to indicate relative quantities in the Stefan-Boltzmann law:
A sample "p" response (from student 1881), using an H-R diagram:
A sample "p" response (from student 1072), using both an H-R diagram and the "box method":