The record in an old-fashioned record player always rotates at the same angular speed. With CDs, the situation is different. For a CD to play properly, the point on the CD where the laser beam shines must have a linear speed vt = 1.25 m/s, as indicated in FIGURE 10-39.

(a) As the CD plays from the center outward, does its angular speed increase, decrease, or stay the same? Explain.

(b) Find the angular speed of a CD when the laser beam is 2.50 cm from its center.

(c) Repeat part (b) for the laser beam 6.00 cm from the center.

(d) If the CD plays for 66.5 min, and the laser beam moves from 2.50 cm to 6.00 cm during this time, what is the CD's average angular acceleration?

T = 6.00 cm r=2.50 cm Laser beam