Physics quiz archive: metric system, significant figures, unit conversions, dimensional analysis

Physics 205A Quiz 1, fall semester 2016
Cuesta College, San Luis Obispo, CA
Sections 70854, 70855, 73320, version 1
Exam code: quiz01bIR6



Sections 70854, 70855, 73320 results

0- 6 :
7-12 :	***** [low = 9]
13-18 :	***************
19-24 :	*************************** [mean = 20.9 +/- 4.8]
25-30 :	********** [high = 30]

Astronomy in-class activity: planet-hunting

Astronomy 210 In-class activity 6 v.16.08.31, fall semester 2016
Cuesta College, San Luis Obispo, CA

Students find their assigned groups of three to four students, and work cooperatively on an in-class activity worksheet to determine where in the sky each naked-eye planet will be observed on a given date (here, September 1, 2016).




Previous posts:

• Astronomy in-class activity: planet-hunting
  spring semester 2016 (February 4, 2016).
• Astronomy in-class activity: planet-hunting
  fall semester 2015 (September 3, 2015).
• Astronomy in-class activity: planet-hunting
  spring semester 2015 (February 4, 2015).
• Astronomy in-class activity: planet-hunting
  fall semester 2014 (September 3, 2014).
• Astronomy in-class activity: planet-hunting
  spring semester 2014 (February 6, 2014).
• Astronomy in-class activity: planet-hunting
  fall semester 2013 (September 5, 2013).
• Astronomy in-class activity: planet-hunting
  spring semester 2013 (February 6, 2013).
• Astronomy in-class activity: planet-hunting
  fall semester 2012 (September 6, 2012).
• Astronomy in-class activity: planet-hunting
  spring semester 2012 (February 2, 2012).
Astronomy in-class activity: planet-hunting
fall semester 2011 (September 1, 2011).
• Astronomy in-class activity: planet-hunting
  spring semester 2011 (February 2, 2011).
• Astronomy in-class activity: planet-hunting
  fall semester 2010 (September 2, 2010).
• Astronomy in-class activity: planet-hunting
  spring semester 2010 (February 4, 2010).

Astronomy quiz archive: Milky Way, cosmology

Astronomy 210 Quiz 7, spring semester 2016
Cuesta College, San Luis Obispo, CA

Section 30674, version 1
Exam code: quiz07N4rK


Section 30674

0- 8.0 :	* [low = 8.0]
8.5-16.0 :	*****
16.5-24.0 :	******** [mean = 19.1 +/- 6.1]
24.5-32.0 :
32.5-40.0 :	** [high = 33.0]

Section 30676, version 1
Exam code: quiz07SrRy


Section 30676

0- 8.0 :	***** [low = 0.0]
8.5-16.0 :	************
16.5-24.0 :	*************** [mean = 20.7 +/- 9.0]
24.5-32.0 :	***********
32.5-40.0 :	******* [high = 36.5]

Physics midterm problem: change in voltmeter reading

Physics 205B Midterm 2, spring semester 2016
Cuesta College, San Luis Obispo, CA

A "AA" alkaline battery with an emf of 1.5 V and an internal resistance of r = 0.90 Ω is attached to an ideal voltmeter, with a R = 2.0 Ω light bulb that is wired in parallel with an open switch. Discuss why the voltmeter will have a lower reading after the switch is closed. Show your work and explain your reasoning using Kirchhoff's rules, Ohm's law, and properties of voltmeters.

Solution and grading rubric:

• p:
  Correct. Recognizes that when the switch is open, the voltmeter will have a non-zero reading, and have a lower (zero) reading when the switch is closed, using one of two similar arguments:
  1. when the switch is open, there is a non-zero ΔV = +1.5 V − I⋅r reading, and when the switch is closed, from Kirchhoff's loop rule the voltage rise of +1.5 V from the emf must now exactly equal the −I⋅r voltage drop of the internal resistance of the battery, such that the voltmeter reading is now zero; or
  2. when the switch is open, there is a non-zero ΔV = − I⋅R reading, and when the switch is closed, since the light bulb R is bypassed by a zero resistance switch, making ΔV = 0.
• r:
  Nearly correct, but includes minor math errors. Does not sufficiently show numerically or qualitatively how voltmeter reading when switch is open is higher versus when the switch is closed.
• t:
  Nearly correct, but approach has conceptual errors, and/or major/compounded math errors. At least has a conceptual understanding of how a voltmeter measures a potential difference, and how the switch changes the current flow when it is open versus when it is closed.
• v:
  Implementation of right ideas, but in an inconsistent, incomplete, or unorganized manner. Some attempt at applying Kirchhoff's rules, Ohm's law, and equivalent resistance.
• x:
  Implementation of ideas, but credit given for effort rather than merit. Approach other than that of applying Kirchhoff's rules, Ohm's law, and properties of voltmeters.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.

Grading distribution:
Sections 30882, 30883
Exam code: midterm02Mc4s
p: 7 students
r: 17 students
t: 4 students
v: 12 students
x: 2 students
y: 0 students
z: 0 students

A sample "p" response (from student 3158):
Another sample "p" response (from student 5433):

Astronomy in-class activity: monolithic collapse hypothesis, stellar populations

Astronomy 210 In-class activity 22 v.16.05.04, spring semester 2016
Cuesta College, San Luis Obispo, CA

Students find their assigned groups of three to four students, and work cooperatively on an in-class activity worksheet to discuss different metallicities and ages of stars in the monolithic collapse hypothesis of the Milky Way.

Astronomy in-class activity: speed of light and look-back time

Astronomy 210 In-class activity 23 v.16.05.04, spring semester 2016
Cuesta College, San Luis Obispo, CA

Students find their assigned groups of three to four students, and work cooperatively on an in-class activity worksheet on the effect of the finite speed of light on look-back time.

Astronomy midterm question: same luminosity, but different temperature and size stars

Astronomy 210 Midterm 2, spring semester 2016
Cuesta College, San Luis Obispo, CA

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

??: If two stars have the same luminosity, is it always true that the star with the lower temperature must be bigger?
qcp: Yes, that's true. A cooler star means that it must be bigger to be of equal luminosity.

Discuss why this answer is correct, 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=20160402221522AAZkrDm.

Solution and grading rubric:

• p:
  Correct. Uses Wien's law, the Stefan-Boltzmann law and/or interprets H-R diagram to demonstrate how a cooler star must be bigger than a hotter star to have the same luminosity.
• 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. At least discussion demonstrates understanding of Wien's law, H-R diagram and/or the Stefan-Boltzmann law.
• 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, H-R diagram and/or the Stefan-Boltzmann law.
• x:
  Implementation/application of ideas, but credit given for effort rather than merit. Discussion not based on Wien's law, H-R diagram and/or the Stefan-Boltzmann law.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.

Grading distribution:
Section 30674
Exam code: midterm02n4s5
p: 12 students
r: 3 students
t: 3 students
v: 1 student
x: 2 students
y: 1 student
z: 0 students

A sample "p" response (from student 1503), using both the "box method" to fill in relative Stefan-Boltzmann law parameters, along with using the diagonal lines on an H-R diagram to compare size:
A sample "x" response (from student 1096), appealing to recent tragic events in pop culture:

Astronomy midterm question: red dwarf same size as white dwarf?

Astronomy 210 Midterm 2, spring semester 2016
Cuesta College, San Luis Obispo, CA

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

??: Can a red dwarf have the same size as a white dwarf?
Bpt: They can have the same size if the red dwarf was dimmer than the white dwarf.

Discuss why this answer is correct, 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=20160402083607AA27vRN.

Solution and grading rubric:

• p:
  Correct. Uses Wien's law, the Stefan-Boltzmann law and/or interprets H-R diagram to demonstrate how a red dwarf can be the same size as a white dwarf by recognizing that:
  1. from Wien's law, the red dwarf is cooler than the white dwarf;
  2. from the Stefan-Boltzmann law (or interpreting an H-R diagram), the lower temperature red dwarf must have a lower luminosity than a white dwarf of the same size.
• 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. At least discussion demonstrates understanding of Wien's law, H-R diagram and/or the Stefan-Boltzmann law.
• 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, H-R diagram and/or the Stefan-Boltzmann law.
• x:
  Implementation/application of ideas, but credit given for effort rather than merit. Discussion not based on Wien's law, H-R diagram and/or the Stefan-Boltzmann law.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.

Grading distribution:
Section 30676
Exam code: midterm02sLoX
p: 37 students
r: 8 students
t: 4 students
v: 3 students
x: 2 students
y: 0 students
z: 0 students

A sample "p" response (from student 0796), using the "box method" to fill in relative Stefan-Boltzmann law parameters:
A sample "p" response (from student 5713), using the diagonal lines on an H-R diagram to compare size:
A sample "p" response (from student 8041):

Astronomy midterm question: star cluster with white dwarfs?

Astronomy 210 Midterm 2, spring semester 2016
Cuesta College, San Luis Obispo, CA

Discuss which H-R diagram is more likely to be a star cluster with type II supernovae (which are deliberately not shown). Explain using the properties of mass and stellar lifetimes, evolution of stars, and star cluster ages.

Solution and grading rubric:

• p:
  Correct. Understands that:
  1. stars in the same cluster are all born at the same time, but massive stars evolve faster than medium-mass stars, which evolve faster than low-mass stars (the "house party" analogy);
  2. medium-mass stars end their main-sequence lifetimes by becoming giants, planetary nebulae, and then white dwarfs;
  3. such that for medium-mass stars to have reached their end stage, massive stars have already gone through all their stages and have exploded as type II supernovae (and no longer appear on an H-R diagram), while low-mass stars have just begun their main-sequence life as red dwarfs.
• 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. Typically at least understands correlation between mass and main-sequence lifetimes.
• v:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Garbled discussion of properties and evolution of stars.
• x:
  Implementation/application of ideas, but credit given for effort rather than merit. Discussion other than that of the properties and evolution of stars.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.

Grading distribution:
Section 30676
Exam code: midterm02n4s5
p: 3 students
r: 6 students
t: 10 students
v: 3 students
x: 0 students
y: 0 students
z: 0 students

A sample "p" response (from student 1503) discussing the "house party model":
Another sample "p" response (from student 1758):

Astronomy midterm question: star cluster with type II supernovae?

Astronomy 210 Midterm 2, spring semester 2016
Cuesta College, San Luis Obispo, CA

Discuss which H-R diagram is more likely to be a star cluster with type II supernovae (which are deliberately not shown). Explain using the properties of mass and stellar lifetimes, evolution of stars, and star cluster ages.

Solution and grading rubric:

• p:
  Correct. Understands that:
  1. stars in the same cluster are all born at the same time, but massive stars evolve faster than medium-mass stars, which evolve faster than low-mass stars (the "house party" analogy);
  2. massive stars end their main-sequence lifetimes by becoming supergiants, then explode as type II supernovae;
  3. such that for massive stars to have reached their end stage, medium-mass have just begun their main-sequence life, while low-mass stars have not yet begun their main-sequence life as red dwarfs.
• 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. Typically at least understands correlation between mass and main-sequence lifetimes.
• v:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Garbled discussion of properties and evolution of stars.
• x:
  Implementation/application of ideas, but credit given for effort rather than merit. Discussion other than that of the properties and evolution of stars.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.

Grading distribution:
Section 30676
Exam code: midterm02sLoX
p: 11 students
r: 15 students
t: 23 students
v: 3 students
x: 1 student
y: 0 students
z: 0 students

A sample "p" response (from student 7074) discussing the "house party model":