Physics
posted by Abigail on .
Figure 1042 shows a uniform disk that can rotate around its center like a merrygoround. 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?

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...