Physics 205A Quiz 5, fall semester 2018
Cuesta College, San Luis Obispo, CA
A Physics 205A student pulls a 15.0 kg box with increasing speed up a ramp with a rope that is parallel to the slope of the ramp. Friction is not negligible. Ignore drag. For this process, the __________ of the box increases.
(A) gravitational potential energy.
(B) translational kinetic energy.
(C) (Both of the above choices.)
(D) (Neither of the above choices.)
Correct answer (highlight to unhide): (C)
The change in translational kinetic energy is given by:
∆KEtr = (1/2)·m·(vf2 – v02).
Since the speed of the box is increasing, vf is faster than v0, and so KEtr is increasing (∆KEtr is positive).
The change in gravitational potential energy is given by:
∆PEgrav = m·g·(yf – y0).
Since yf is higher than y0, then PEgrav also increases (∆PEgrav is positive).
Sections 70854, 70855
Exam code: quiz04JuR4
(A) : 17 students
(B) : 7 students
(C) : 28 students
(D) : 0 students
Success level: 54%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.75
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