Physics

Figure 10-42 shows a uniform disk that can rotate around its center like a merry-go-round. The disk has a radius of 2.00 cm and a mass of 20.0 grams and is initially at rest. Starting at time t = 0, two forces are to be applied tangentially to the rim as indicated, so that at time t = 1.25 s the disk has an angular velocity of 270 rad/s counterclockwise. Force F1 has a magnitude of 0.160 N. What magnitude is required of force F2?

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  1. Use Summation of
    Torque(T) = Inertia(I)*Acceleration(alpha)

    T=I*alpha, and we know I = (1/2)(m)(r)^2
    T=(F1+F2)r
    alpha= dw/dt= 270rad/1.25s ( w is the given angular velocity)
    so (F1+F2)*r=(1/2)(m)(r)^2 * alpha
    solve for F2...

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  2. Yes to the response from 2015, but replace (F1+F2) with (F2-F1)

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