A machinist turns the power on to a grinding wheel,at rest,at time t = 0 s.The wheel accelerates uniformly for 10 s and reaches the operating angular velocity of 29 rad/s.The wheel is run at that angular velocity for 27 s and then power is shut off.The wheel slows down uniformly at 2.7 rad/s² until the wheel stops.In this situation,the average angular velocity in the time interval from t = 0 s to t = 25 s is closest to: A)17 rad/s B)15 rad/s C)13 rad/s D)11 rad/s E)8.7 rad/s

Question

Quizplus · Accepted Answer

The wheel accelerates uniformly to 29 rad/s in 10 s, so the average angular velocity during acceleration is (0 + 29)/2 = 14.5 rad/s. For the next 15 s (from t = 10 s to t = 25 s), the wheel runs at 29 rad/s. The average angular velocity over the entire 25 s is [(14.5 * 10) + (29 * 15)] / 25 = 17 rad/s.

A Machinist Turns the Power on to a Grinding Wheel,at