A bead of mass m= 5.00 kg is released from point A and slides on a frictionless track. Height at point A is 5.00 m, height at point B is 3.20 m, and height at point C is 2.00 m. Determine (a) the bead's speed at points B and C (b) the net work done by the force of gravity in moving the bead from A to C.