Physics quiz question: train coming to stop

Physics 5A Quiz 2, Spring Semester 2008
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 1/e, Problem 2.35(c)

[3.0 points.] A train is traveling 34.0 m/s in the +x direction when the brakes are applied. It slows down with a constant acceleration to a complete stop in a time of 110 s. How far has the train traveled at the end of 110 s?
(A) 617 m.
(B) 1.87e3 m.
(C) 3.74e3 m.
(D) 3.67e4 m.

Correct answer: (B)

Response (C) is the distance traveled by the train if it maintained its velocity of +34.0 m/s for 110 s. The correct response (B) is the distance traveled by the train with an initial speed of +34.0 m/s and a final speed of 0 m/s, for a constant deceleration during the 110 s. Response (A) is delta(t)^2/(2*g), and response (D) is v_ix*g*delta(t).

Student responses
Sections 4987, 4988
(A) : 1 student
(B) : 33 students
(C) : 12 students
(D) : 0 students