Problems Center of Mass 9. Two bowling balls are at rest on top of a uniform wooden plank with their centers of mass located as in Figure P83. The plank has a mass of 5.00 kg and is 1.00 m long. Find the hori- zontal distance from the left end of the plank to the center of mass of the plank-bowling balls system. Figure P8.9 ZTorque=erF=ErF sine