A student uses a plumb bob to verify that the doorjamb in a car is vertical. As the car pulls away from a stop, the student observes that the string now makes an angle θ with the doorjamb. What is the acceleration of the car?
A) g sin θ
B) g cos θ
C) g tan θ
D) g θ
E) θ

Question

Quizplus · Accepted Answer

The angle θ indicates that the plumb bob is deflected due to the horizontal acceleration of the car. The horizontal component of the tension in the string is equal to the mass times the acceleration (ma), and the vertical component is equal to the weight (mg). Therefore, tan θ = a/g, which implies a = g tan θ.

A Student Uses a Plumb Bob to Verify That the Doorjamb