Disk Y of rotational inertia Iy about its center is held at rest above disk X of rotational inertia Ix about its center. Disk X rotates about its center with an angular velocity +w. Disk Y is slowly lowered onto disk X until both disks are in contact and travel together with a common angular velocity. A graph of disk X's angular acceleration a as a function of time is shown. Which of the following equations can a student use to verify that angular momentum is conserved in the situation? Justify your selection. Ixw = (Ix + Iy) (w +a5t), because the final velocity of the two-disk system is equal to the initial velocity of disk X plus the magnitude of the area bound by the curve and the horizontal axis from to . A B Ixw = (IxIx) (w +a5t), because the final velocity of the two-disk system is equal to the initial velocity of disk X minus the magnitude of the area bound by the curve and the horizontal axis from to . Ixw = (Ix + Iy) (W - 5t), because the final velocity of the two-disk system is equal to the initial velocity of disk X minus the magnitude of the area bound by the curve and the horizontal axis from to . Ixw = (IxIx) (w - a5t), because the final velocity of the two-disk system is equal to the initial velocity of disk X minus the magnitude of the area bound by the curve and the horizontal axis from to t. Acceleration Angular of Disk X 0- -1 -210- -3- -4 .910- -6 0 t t Time t3 tA