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

Physics 205A Quiz 1, fall semester 2019
Cuesta College, San Luis Obispo, CA
Sections 70854, 70855
Exam code: quiz01B34t



Sections 70854, 70855 results

0- 6 :	* [low = 6]
7-12 :	****
13-18 :	*************
19-24 :	*********************** [mean = 21.4 +/- 5.7]
25-30 :	************** [high = 30]

Physics quiz question: dimensional expansion of aluminum rod

Physics 205A Quiz 7, fall semester 2018
Cuesta College, San Luis Obispo, CA

An aluminum bar (linear expansion coefficient 2.3×10^–5 K^–1) has a length of 0.500 m, and a cross-sectional area of 4.0×10^–4 m² at room temperature (20.0° C). As the temperature of the bar is raised, its __________ will increase.
(A) length.
(B) cross-sectional area.
(C) (Both of the above choices.)
(D) (Neither of the above choices.)

Correct answer: (C)

The relation between the change in length (along any dimension) ∆L due to a temperature change ∆T is given by:

α·∆T = ∆L/L.

With a temperature increase, the length, width, and height of the bar will all proportionally expand, such that both the length and the cross-sectional area of the bar will increase.

Sections 70854, 70855
Exam code: quiz07PeA7
(A) : 25 students
(B) : 3 students
(C) : 22 students
(D) : 0 students

Success level: 44%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.13

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

Physics 205A Quiz 1, fall semester 2018
Cuesta College, San Luis Obispo, CA
Sections 70854, 70855 version 1
Exam code: quiz01CrR4



Sections 70854, 70855 results

0- 6 :
7-12 :	**** [low = 12]
13-18 :	*****************
19-24 :	********************* [mean = 22.2 +/- 5.3]
25-30 :	******************** [high = 30]

Physics quiz question: expansion of aluminum rod

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

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

Correct answer: (D)

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

α·∆T = ∆L/L,

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

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

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

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

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

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

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

Physics 205A Quiz 1, fall semester 2017
Cuesta College, San Luis Obispo, CA
Sections 70854, 70855 version 1
Exam code: quiz01D4mP



Sections 70854, 70855 results

0- 6 :
7-12 :	** [low = 12]
13-18 :	****************
19-24 :	************************************ [mean = 20.7 +/- 3.6]
25-30 :	**** [high = 30]

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]

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

Physics 205A Quiz 1, fall semester 2015
Cuesta College, San Luis Obispo, CA
Sections 70854, 70855, 73320, version 1
Exam code: quiz01rdBL



Sections 70854, 70855, 73320 results

0- 6 :
7-12 :	** [low = 9]
13-18 :	*****************
19-24 :	****************************** [mean = 23.2 +/- 4.9]
25-30 :	****************************** [high = 30]

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

Physics 205A Quiz 1, fall semester 2014
Cuesta College, San Luis Obispo, CA
Sections 70854, 70855, 73320, version 1
Exam code: quiz01w34K



Sections 70854, 70855, 73320 results

0- 6 :
7-12 :	***** [low = 9]
13-18 :	**********************
19-24 :	******************************* [mean = 21.8 +/- 5.4]
25-30 :	******************* [high = 30]

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

Physics 205A Quiz 1, fall semester 2013
Cuesta College, San Luis Obispo, CA
Sections 70854, 70855, 73320, version 1
Exam code: quiz01cH3E

Sections 70854, 70855, 73320 results

0- 6 :	** [low = 6]
7-12 :	*******
13-18 :	***********
19-24 :	********************** [mean = 23.0 +/- 6.7]
25-30 :	********************************** [high = 30]

Physics quiz question: expansion of prototype meter

Physics 205A Quiz 7, fall semester 2012
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Comprehensive Problem 13.101

"Platinum-Iridium meter bar"
National Institute of Standards and Technology
commons.wikimedia.org/wiki/File:Platinum-Iridium_meter_bar.jpg

The international prototype meter[*][**] was set by the distance between two markings on a platinum-iridium alloy bar (α = 8.7×10^–6 K^–1) at 0° C. To increase the distance between these markings by 0.01 mm, the temperature should be raised by:
(A) 0.001° C.
(B) 0.01° C.
(C) 0.1°.
(D) 1° C.

[*] "Differences...lie within 0.01 millimetre," bipm.org/en/CGPM/db/1/1/.
[**] "Pt90/Ir10 coefficient of thermal expansion @20-100° C," goodfellow.com/E/Platinum-Iridium.html.

Correct answer: (D)

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

α·∆T = ∆L/L,

such that:

∆T = ∆L/(α·L) = (0.01×10^–3 m)/((8.7×10^–6 K^–1)·(1 m)) = 1.14942528736 K,

or to one significant figure, the change in temperature is 1 K or 1° C.

Sections 70854, 70855
Exam code: quiz07Di5k
(A) : 5 students
(B) : 6 students
(C) : 4 students
(D) : 35 students

Success level: 70%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.09

Physics quiz question: "bloit"

Physics 205A Quiz 1, fall semester 2012
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 1.25

According to a popular series of computer games[*], a bloit is defined as "the distance the king's favorite pet runs in an hour." If the distance of one bloit is 3,529 feet, how fast does the king's favorite pet run, in units of m/s? (There are 3.2808399 feet in one meter.)
(A) 0.2988 m/s.
(B) 3.216 m/s.
(C) 3.347 m/s.
(D) 17.93 m/s.

[*] zork.wikia.com/wiki/Bloit.

Correct answer (highlight to unhide): (A)

The speed of the king's favorite pet is 1 bloit/h = 3,529 ft/h. To convert this into m/s:

3,529 ft/h × (1 h)/(60 min) × (1 min)/(60 s) × (1 m)/(3.2808399 ft) = 0.29878866621 m/s,

or to four significant figures, 0.2988 m/s.

(Response (B) is 3,529 ft/h multiplied by (3.2808399/3,600); response (C) is the inverse of response (A); and response (D) is 3,529 ft/h divided by (60×3.2808399).)

Sections 70854, 70855
Exam code: quiz01bL0t
(A) : 44 students
(B) : 4 students
(C) : 1 student
(D) : 12 students

Success level: 72%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.40

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

Physics 205A Quiz 1, fall semester 2012
Cuesta College, San Luis Obispo, CA

Sections 70854, 70855, version 1
Exam code: quiz01bL0t


Sections 70854, 70855

0- 6 :
7-12 :	***** [low = 12]
13-18 :	**********
19-24 :	******************** [mean = 23.2 +/- 5.6]
25-30 :	************************** [high = 30]

Physics quiz question: distance of a light "hellasecond"

Physics 205A Quiz 1, fall semester 2011
Cuesta College, San Luis Obispo, CA

Given that the speed of light in vacuum is 3.00×10⁸ m/s, how many meters would light travel in 1 Hs (1 "hellasecond" = 10²⁷ s)?
(A) 3.33×10³⁶ m.
(B) 3.00×10^–19 m.
(C) 3.33×10¹⁸ m.
(D) 3.00×10³⁵ m.

Correct answer (highlight to unhide): (D)

The speed of light in vacuum is c = 3.00×10⁸ m/s, and the relation between speed, distance, and elapsed time is:

c = ∆x/∆t,

such that solving for ∆x gives:

∆x = c⋅∆t = (3.00×10⁸ m/s)⋅(1e×10²⁷ s) = 3.00×10³⁵ m.

(Response (A) is 1/(c⋅∆t); response (B) is c/∆t, and response (C) is ∆t/c.)

Sections 70854, 70855
Exam code: quiz01unI7
(A) : 3 students
(B) : 10 students
(C) : 1 student
(D) : 42 students

Success level: 74%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.33

Compare to results of a similar "hella-" problem asked of second-semester college physics students (fall semester 2010).

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

Physics 205A Quiz 1, fall semester 2011Cuesta College, San Luis Obispo, CASections 70854, 70855, version 1Sections 70854, 70855 results
Exam code: quiz01unI7

 0- 6 :  7-12 : *******  [low = 9]13-18 : ********************19-24 : ************************  [mean = 19.5 +/- 4.8]25-30 : ******  [high = 30]

Physics quiz question: "hellameter"

Physics 205B Quiz 1, Fall Semester 2010
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 22.17

How long does it take light to travel 1 Hm (1 "hellameter" = 10^27 m) in vacuum?
(A) 3.33e–36 s.
(B) 3.00e–19 s.
(C) 3.33e+18 s.
(D) 3.00e+35 s.

Correct answer: (C)

The speed of light in vacuum is c = 3.00e+8 m/s, and the relation between speed, distance, and elapsed time is:

c = ∆x/∆t,

such that solving for time gives:

∆t = (∆x)/c = (3.00e+8 m/s)/(1e+27 m) = 3.33e+18 s.

Response (A) is 1/(c*∆x); response (B) is c/∆x, and response (D) is c*∆x.

Student responses
Section 70856
(A) : 0 students
(B) : 3 students
(C) : 7 students
(D) : 3 students

Success level: 54%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.75

Found physics: hella-

20100709652
http://www.flickr.com/photos/waiferx/4806032390/
Originally uploaded by Waifer X

...or supposedly 10^27, in the metric system.