Physics quiz question: thermal contraction of opening in metal plate

Physics 205A Quiz 7, Fall Semester 2008
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 1/e, Conceptual Question 13.4

[3.0 points.] A square opening is made in a metal plate. The metal plate is cooled down from room temperature to a final temperature of 100 K. What happens to the size of the square opening as the metal plate cools down?
(A) The square opening becomes smaller.
(B) The square opening becomes larger.
(C) The square opening remains the same size as before.
(D) (Not enough information is given.)

Correct answer: (A)

All dimensions in a rigid object will contract proportionally when cooled (and expand proportionally if heated).

Student responses
Sections 70854, 70855
(A) : 26 students
(B) : 8 students
(C) : 2 students
(D) : 0 students

"Difficulty level": 72%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.60