In an Experiment,a Student Brings Up the Rotational Speed of a Piece

Multiple Choice

In an experiment,a student brings up the rotational speed of a piece of laboratory apparatus to 30.0 rpm.She then allows the apparatus to slow down uniformly on its own,and counts 240 revolutions before the apparatus comes to a stop.The moment of inertia of the apparatus is known to be 0.0850 kg • m².What is the magnitude of the retarding torque on the apparatus?

A) 0.0425 N • m
B) 0.159 N • m
C) 0.0787 N • m
D) 0.000278 N • m
E) 0.0000136 N • m