Following a collision between a large spacecraft and an asteroid, a copper disk of radius 28.0 m and thickness 1.20 m, at a temperature of 850°C, is floating in space, rotating about its axis with an angular speed of 20.0 rad/s. As the disk radiates infrared light, its temperature falls to 20.0°C. No external torque acts on the disk.
(a) Find the change in kinetic energy of the disk.
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(b) Find the change in internal energy of the disk.
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(c) Find the amount of energy it radiates.