20111215

Physics quiz question: thermal expansion of different cross-section bars

Physics 205A Quiz 7, fall semester 2011
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 13.9

A 1.0 cm2 cross-sectional area steel bar is heated up such that its length extends by by 0.1 mm. To extend a 2.0 cm2 cross-sectional area steel bar by 0.1 mm, it must experience a temperature change __________ the temperature change of the 1.0 cm2 cross-sectional area steel bar. (The bars have the same length.)
(A) smaller than.
(B) the same as.
(C) larger than.
(D) (Not enough information is given.)

Correct answer: (B)

The thermal expansion of a bar of length L is given by:

L = L*β*T,

and does not depend on the cross-sectional area of the bar.

Sections 70854, 70855
Exam code: quiz07h3A7
(A) : 15 students
(B) : 20 students
(C) : 17 students
(D) : 0 students

Success level: 38%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.71

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