Bored with work? Try spinning!

The other day while I was waiting in my lab for our microscope laser to warm up I got bored so I ended up spinning around in one of the chairs. While I was doing this I realized that I was pulling my legs in and pushing them out as I spun. As I was doing this I was speeding up as pulled my legs in, and I was slowing down as I let my legs stick out again. Thinking back to what was happening it makes a fun connection with our angular momentum topic that we covered in class. 

As I pulled my legs in, I decreased my moment of inertia (I). In order for the conservation of angular momentum to hold true, my angular velocity would need to increase to compensate for this, which it did! In the opposite sense, when I let my legs stick out again my angular velocity decreased because I was increasing my moment of inertia. An interesting aspect about this though is that my kinetic energy was actually increasing as I pulled my legs in and my angular velocity increased. But where would the extra energy come from to raise the kinetic energy of my system? It comes from the work that I did when I pulled my legs inward, that would have to counteract the centripetal acceleration that would pull them outwards. Anyways, good luck during exam week everyone!