Physics midterm question: car going over round hill

Physics 205A Midterm 1, fall semester 2011
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Conceptual Question 5.2

Which free-body diagram (A)-(F) represents a car going over a round hill, traveling slow enough such that there is still contact with the top of the hill? Clearly circle your answer below.


Correct answer: (C)

The car experiences a downwards weight force, and an upwards normal force from the road. Since the car is going over a round hill, the net force must point downwards (towards the center of its (momentarily) uniform circular motion), such that the normal force must be less than the weight force.

Sections 70854, 70855
Exam code: midterm01w4Sh
(A) : 2 students
(B) : 2 students
(C) : 18 students
(D) : 15 students
(E) : 3 students
(F) : 13 students

Success level: 34%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.30