Energy in rotational motion
A frictionless pulley has the shape of a uniform solid disk of mass 2.50 kg and radius 20.0 cm. A 1.50kg stone is attached to a very light wire that is wrapped around the rim of the pulley, and the system is released from rest. (a) How far must the stone fall so that the pulley has 4.50 J of kinetic energy? (b) What percent of the total kinetic energy does the pulley have?
Help, I really don't know how to start on this one. I only know that the pulley's kinetic energy is given by
K = 1/2 w^2I where w is the angular velocity and I is the moment of inertia. From this I can find the pulley's angular velocity when it's kinetic energy is 4.50, but I don't know how/if that can help me and what to do from there....
