Following a collision in outer space, a copper disk at $800\backslash$deg C is rotating about its axis with an angular speed of $27\mathrm{.}0$ rad$/$s$.$ As the disk radiates infrared light, its temperature falls to $20\mathrm{.}0\backslash$deg C$.$ No external torque acts on the disk. $($a$)$ Does the angular speed change as the disk cools? It decreases. It increases. It stays the same. Explain how it changes or why it does not. This answer has not been graded yet. $($b$)$ What is its angular speed at the lower temperature? rad$/$s