Problem D7:
Initially, a disk is spinning. The disk has a mass of m_{0} and
a radius of R_{0}. The kinetic energy of rotation that it initially
has is E_{0}. Then, another disk (initially not rotating) is placed on top of the first
one. The second disk has a mass of n_{1}m_{0} and a radius of
n_{2}R_{0}. The axes of the two disks are in line.
There is friction between the two disks, and the two disks end up spinning at the
same rate. What is the final kinetic energy of rotation of the two disks?
If the final rotational energy of the system is E = E_{0}/n_{3},
what is n_{3}? Note: n_{1}, n_{2}, and n_{3}
are unitless.

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