At the instant r = 1.5 m, the 5-kg disk is given a speed of v = 5 m/s, perpendicular to...

At the instant r = 1.5 m, the 5-kg disk is given a speed of v = 5 m/s, perpendicular to the elastic cord. Determine the speed of the disk and the rate of shortening of the elastic cord at the instant r = 1.2 m. The disk slides on the smooth horizontal plane. Neglect its size. The cord has an unstretched length of 0.5 m.