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Homework Help: Exam Review Help!

  1. Oct 29, 2009 #1
    1. The problem statement, all variables and given/known data
    Flywheels are large, massive wheels used to store energy. They can be spun up slowly, then the wheel's energy can be released quickly to accomplish a task that demands high power. An industrial flywheel has a 1.5 m diameter and a mass of 250 kg. Its maximum angular velocity is 1200 rpm. A motor spins up the flywheel with a constant torque of 50 Nm. How long does it take the flywheel to reach top speed?

    This gave me...
    radius = .75m
    mass = 250kg
    max Angular Velocity = 125.7 radians/second
    torque = 50 Nm

    2. Relevant equations
    I wasn't sure how to approach the problem. I was trying to figure out how to find angular acceleration, but unsure if that was possible. Please let me know the steps.
  2. jcsd
  3. Oct 29, 2009 #2


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    Homework Helper

    Torque T = I*α. Find the moment of inertia of the flywheel. Torque is given. Find α, and then t.
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