In the figure the lower disk, of mass 430 g and radius 3.4 cm, is rotating at 180 rpm on a frictionless shaft of negligible radius. The upper disk, of mass 260 g and radius 2.4 cm, is initially not rotating. It drops freely down onto the lower disk, and frictional forces bring the two disks to a common rotational speed. (Figure 1) Figure (a) < $$ (b) 1 of 1 > Part A Find the common speed. Express your answer in revolutions per minute. Wf = Submit Part B f = Submit Find the fraction of the initial kinetic energy lost to friction. Express your answer as a percentage. Request Answer Provide Feedback 159 Request Answer rpm % Next >