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Dynamics

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a flywheel has an angular speed of 1200rev/min when its motor is turned off.the wheel attains constant decelerations of 1.5rad/s2 due to friction in its bearing.determine the time required for the wheel to come to rest and the numer of revolutions the wheel makes before it comes to rest.

  • Dynamics -

    Wi= 1200 rev/min = 20 rev/sec
    = 20*2*pi rad/sec
    Wf = 0; alpha= -1.5 rad/s^2

    Wf = Wi + alpha*t
    0 = 40*pi - 1.5*t
    t = 40*pi/1.5 = 84 sec
    Now,
    theta = Wi*t + (1/2)*alpha*t^2

    Plug in the values in this eqn. to get theta - the rotation of the wheel (in radians)before it comes to halt. Divide the result by 2*pi to convert into no. of revolutions.

  • Dynamics -

    Please help me to elaborate the answer as i tried but couldn't

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