The outer edge of the grooved area of a long-playing record is at a radial distance 36 cm from the center; the inner edge is at a radial distance of 15 cm. The record rotates at 4.5 rev/min. The needle of the pick-up arm takes 2.3 minutes to move uniformly from the outer edge to the inner edge.
What is the radial speed of the needle?_______ m/s
What is the speed of the outer edge relative to the needle?_____ m/s
What is the speed of the inner edge relative to the needle? m/s Suppose the phonograph is turned off, and the record uniformly and stops rotating after 10 s. What is the angular acceleration? ______rad/s2