20180925

Physics quiz question: distance traveled vs. displacement magnitude

Physics 205A Quiz 3, fall semester 2018
Cuesta College, San Luis Obispo, CA

A Physics 205A student throws a basketball with an initial velocity vector that has x- and y-components:
v0x = +5.5 m/s,
v0y = +4.2 m/s.
Neglect air resistance. From being launched to reaching the highest height of its trajectory, the basketball's distance traveled will be __________ the magnitude of its displacement.
(A) less than.
(B) equal to.
(C) greater than.
(D) (Not enough information is given.)

Correct answer (highlight to unhide): (C)

For projectile motion, the distance traveled is measured along its curved trajectory, and is longer than the magnitude of the displacement, which is the length of the straight-line vector that starts from the release point, and ends at the highest point of its trajectory.

(Response (A) can never be true for any possible path taken by an object. Response (B) can only be true for an object traveling along a straight-line with no reversals in direction.)

Sections 70854, 70855
Exam code: quiz03pRH5
(A) : 4 students
(B) : 12 students
(C) : 40 students
(D) : 0 students

Success level: 71%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.53

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