A circular saw is powered by a motor.When the saw is used to cut wood, the wood exerts a torque of 0.80 N∙m on the saw blade.If the blade rotates with a constant angular velocity of 20 rad/s the work done on the blade by the motor in 1.0 min is:
A)0 J
B)480 J
C)960 J
D)1500 J
E)1800 J

Question

Quizplus · Accepted Answer

The work done on the blade by the motor is given by the formula:
Work = torque x angular displacement 
Since the blade rotates with a constant angular velocity, the angular displacement is given by: 
angular displacement = angular velocity x time 
So, the work done on the blade in 1.0 minute (60 seconds) is: 
Work = torque x angular velocity x time 
Work = 0.80 N∙m x 20 rad/s x 60 s 
Work = 960 J 
Therefore, the answer is choice C, 960 J.

A Circular Saw Is Powered by a Motor