Part A An electric fan is turned off, and its angular velocity decreases uniform

Question

Part A An electric fan is turned off, and its angular velocity decreases uniformly from 520 rev/min to 230 rev/min in a time interval of length 3.90 s Find the angular acceleration in rev/s My Answers Give Up gy of a Part B find the number of revolutions made by the motor in the time interval of length 3.90 s Canned F Inertia and is Theorem 70 Part C 9.100 How many more seconds are required for the fan to come to rest if the angular acceleration remains constant at the value calculated in part A? 9.10 e 1 47 0 se 1 48 se 1 49 Print A

Explanation / Answer

Given,

w0 = 520 rev/min = 8.67 rev/s ; w = 230 rev/s = 3.83 rev/s; t = 3.9 s

A)We know from eqn in circular motion

w = w0 + alphaw t

alpha = (w - w0)/t

alpha = (3.83 - 8.67)/3.9 = -1.24 rev/s^2

Hence, alpha = - 1.24 rev/s^2

(Negative sign can be ignored for magnitude only)

B)From another eqn in circular motion

theta = w0t + 1/2 alpha t^2

theta = 8.67 x 3.9 + 0.5 x -1.24 x 3.9^2 = 24.38 rad

Hence, N = 24.38 rev

C)t = (0 - w)/alpha

t = (0 - 3.83)/-1.24 = 3.09 s

Hence, t = 3.09 s

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