 What I have here is a lazy Susie has a very good bearing. So the friction is pretty low So once I accelerated it, it will almost continue at the same angular velocity for a very long time now if you apply a conservation of Angler momentum on this situation, there is a few things that we can observe first Initially, there is no angular momentum. So no rotation at all. I need to apply some torque in order to get it to speed The longer I apply the torque the faster you will get Torque times time gives me the change in angular momentum So now it's rotating Now a classical thing that we can do is we can change the Angler or the rotational inertia of this platform. What if I add some masses to the edges? So now initially the system consists of a rotating platform and two masses that do not rotate. So initially there's only the angular momentum of the rotating platform Once I drop Those two guys on the platform. They will start rotating with it so We would expect what that? The platform speeds up continues traveling at the same speed or slows down the moment. I drop this Now let's have a look. It clearly slowed down because now the total rotational inertia is bigger and the initial angular momentum of the platform is now distributed on the platform and the two masses that rotate as well