Here is the problem, I've been trying for a day but can't seem to come up with the right answer. A 4.0 kg mass is connected by a massless string over a massless and frictionless pulley to the center of an 8.0 kg wheel. Assume that the wheel has a radius of .5 m and a moment of inertia of 2.0 kg*m^2. The mass is released from rest at a height of 2.0 m above the ground. What will its speed be just before it strikes the ground? (Hint: Apply conservation of mechanical energy.) Well, any help would be appreciated. I've tried cons. of mech. energy, but I come up with a wrong answer.