20151003

Physics quiz question: forces pushing on still-stuck suitcase, crate

Physics 205A Quiz 3, fall semester 2015
Cuesta College, San Luis Obispo, CA


A horizontal force of 45 N is applied to the left on a suitcase, and another horizontal force of 45 N is applied to the left on a crate. The suitcase is more massive than the crate. Both the suitcase and the crate are motionless, and both have the same static friction coefficient µs with the horizontal floor.

The __________ has a greater magnitude net force exerted on it.
(A) suitcase.
(B) crate.
(C) (There is a tie.)
(D) (Not enough information given.)

Correct answer (highlight to unhide): (C)

Since the suitcase is stationary, its motion is constant (with zero velocity). Thus the net force of all the forces acting on the suitcase must equal zero, due to Newton's first law. Similarly for the crate, which is also stationary, and thus the net force of all the forces acting on the crate must also equal zero, due to Newton's first law.

Sections 70854, 70855, 73320
Exam code: quiz03re3T
(A) : 15 students
(B) : 7 students
(C) : 51 students
(D) : 1 student

Success level: 70%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.48

No comments:

Post a Comment