A bicycle travels 141 m along a circular track of radius 30 m. What is the angular displacement in radians of the bicycle from its starting position?
A)1.0 rad
B)1.5 rad
C)3.0 rad
D)4.7 rad
E)9.4 rad

Question

Quizplus · Accepted Answer

The circular path can be thought of as a part of a circle of radius 30 m. The circumference of this circle is 2πr = 60π m.
The fraction of the circle that the bicycle travels is 141/60π.
The angle in radians that the bicycle travels is equal to the fraction of the circle it travels, i.e., 
θ = (141/60π) × 2π = 4.7 rad (rounded to one decimal place)
Therefore, the answer is D) 4.7 rad.

A Bicycle Travels 141 M Along a Circular Track of Radius