An electric fan is turned off, and it\'s angular velocity decreases uniformly fr

Question

An electric fan is turned off, and it's angular velocity decreases uniformly from 630 rev/min to 220 rev/min in 5.0 seconds. A. Find the angular acceleration in rev/s^2. B. Find the number of revolutions made by the motor in the 5 second interval. C. How many more seconds are required for the far to come to rest if the angular acceleration remains constant at the value calculated in part A? An electric fan is turned off, and it's angular velocity decreases uniformly from 630 rev/min to 220 rev/min in 5.0 seconds. A. Find the angular acceleration in rev/s^2. B. Find the number of revolutions made by the motor in the 5 second interval. C. How many more seconds are required for the far to come to rest if the angular acceleration remains constant at the value calculated in part A? A. Find the angular acceleration in rev/s^2. B. Find the number of revolutions made by the motor in the 5 second interval. C. How many more seconds are required for the far to come to rest if the angular acceleration remains constant at the value calculated in part A?

Explanation / Answer

angular accleration a = rate of change of angular velocity

a = (wf - Wi)/t

Wf = 220 * 2pi/60 = 23.03 rad/s

Wi = 630 * 2 pi/60 = 66 rad/s

ang accleration a = (23.03- 66)/5

ang accleration = - 8.6 rad/s^2

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part B

let the number of revolutions made is n

By f^2 = 1^2 - 2

2 * 8.6 * = (66)^2 - (23.03)^2

= 222.41 rad = 222.41* 180/ = 12743.15

n = 12743.15/360

n =35 evolutions

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C)
Wf - Wt = At

t = Wf/A

t = 66/8.65

t = 7.63 secs

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