vl Il / Perspective View Top View Top View Figure 1 Figure 2 A disk of mass i slides with negligible friction to the right with speed y; on a horizontal table. The disk collides elastically with a uniform rod of length / that is at rest and free to pivot about one end, as shown in Figure 1 above. The disk rebounds to the left with speed v, and the rod rotates with friction and stops at a final angle #, from its initial position, as shown in Figure 2. Immediately after the collision, the rod has angular speed ., and the rod comes to rest a time /At after the collision. If the rotational inertia of the rod about the pivot is I, the average torque exerted on the rod by friction while the rod is coming to rest is a) & X 7 D)