07:55
University Physics with Modern Physics
A uniform, 8.40 -kg, spherical shell 50.0 $\mathrm{cm}$ in diameter has four small 2.00 -kg masses attached to its outer surface and equally spaced around it. This combination is spinning about an axis running through the center of the sphere and two of the small masses (Fig. P10.60). What friction
torque is needed to reduce its angular speed from 75.0 rpm to 50.0 rpm in 30.0 s?