Two uniform circular discs are rotating
independently in the same direction around
their common axis passing through their
centres. The moment of inertia and angular
velocity of the first disc are 0.1 kg-m² and 10
rad s^–1 respectively while those for the second
one are 0.2 kg-m² and 5 rad s^–1 respectively. At
some instant they get stuck together and start
rotating as a single system about their common
axis with some angular speed. The kinetic
energy of the combined system is :