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Homework Help: Rotational Kinetic energy to Electrical energy

  1. Oct 23, 2008 #1
    1. The problem statement, all variables and given/known data
    I have a motor with WK^2 = 4 lb-ft turning at 5400 RPM (3 * base speed) and I want to slow it to 1530 RPM (.85 * base speed). The motor is a 25HP 4 pole with a base speed of 1800 RPM.

    How much electrical energy must I absorb?

    2. Relevant equations

    3. The attempt at a solution
    I have calculated the kinetic energy of the motor @ 5400 RPM and 1530 RPM using
    Ke = 1/2 * Inertia * omega^2 and found the total Rotational energy lost. For Ke @ 5400 RPM I have calculated 3067 J and @1530 RPM I have calculated 869 J for a difference of 2197 J.
  2. jcsd
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