physics

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A cooling fan is turned off when it is running at 870 rev/min. It turns 1200 revolutions before it comes to a stop.
What was the fan's angular acceleration, assumed constant?
How long did it take the fan to come to a complete stop?

  • physics -

    870 rpm = 91.1 rad/s
    The average angular velocity during decleration is half that, or
    w,av = 45.6 rad/s
    The time it takes to stop is
    2400*2*pi/45.6 = 165 seconds

    If the want the angular acceleration in radians/sec^2, use
    alpha = (91.1 rad/s)/165 s

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