Physics quiz question: laboratory cart collision

Physics 205A Quiz 4, fall semester 2011
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 7.55

(Ignore friction, drag, and other external forces during this brief collision.) A laboratory cart moving to the right on a horizontal track collides elastically with a more massive cart moving to the left. Based solely on the information given, __________ must be conserved.
(A) momentum.
(B) kinetic energy.
(C) (Both of the above choices.)
(D) (None of the above choices.)

Correct answer (highlight to unhide): (C)

Negligible net external force and brief time duration for this collision makes the external impulse on this system zero, such that momentum is conserved. Since the carts are described as colliding elastically, then kinetic energy is also conserved.

Sections 70854, 70855
Exam code: quiz04iMpL
(A) : 2 students
(B) : 5 students
(C) : 44 students
(D) : 0 students

Success level: 86%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.45

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