Two disks are located on an axle as shown in Figure P9.46. The lower disk is initially s...

Two disks are located on an axle as shown in Figure P9.46. The lower disk is initially spinning at 50 rad/s, and the upper one is not spinning. The upper disk then falls onto the lower disk, and they stick together. (a) Is there a torque on the lower disk? On the upper disk? (b) Identify a system for which the external torque is zero so that the angular momentum is conserved. (c) What is the initial angular momentum of your system? (d) What is the final angular momentum of your system? Express your answer in terms of the final angular velocity of the two disks. (e) Find