Cuesta College, San Luis Obispo, CA
Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 14.33 (extended)
Students were asked the following clicker question (Classroom Performance System, einstruction.com) at the start of their learning cycle:
500 g of ice at -10 degrees C is placed into 500 g of 0 degrees C water, in a container that is insulated from the environment. As this system reached thermal equilibrium:
(A) ice melted.
(B) water froze.
(C) (Both of the above choices.)
(D) (None of the above choices.)
(E) (I'm lost, and don't know how to answer this.)
Sections 30880, 30881
(A) : 4 students
(B) : 15 students
(C) : 4 students
(D) : 7 students
(E) : 0 students
This question was asked again after displaying the tallied results with the lack of consensus, with the following results. No comments were made by the instructor, in order to see if students were going to be able to discuss and determine the correct answer among themselves.
Sections 30880, 30881
(A) : 2 students
(B) : 18 students
(C) : 5 students
(D) : 6 students
(E) : 0 students
Correct answer: (B)
Heat will flow from the water to the ice, which results in water freezing (as it is already at 0 degrees C), and ice warming up from its initial temperature. Ice does not melt during this process, as would have to be warmed up entirely to 0 degrees C, in which case is not consistent with heat leaving the water in this isolated system.
Pre- to post- peer-interaction gains:
pre-interaction correct =50%
post-interaction correct = 58%
Hake, or normalized gain
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