Chapter 10, Problem 77GP

Predict/Calculate Playing a CD The record m 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 v_t = 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. b If the CD plays for 66.5 mm, and the laser beam moves from 2.50 cm to 6.00 cm during this time what is the CD's average angular acceleration?

Figure 10-39

Problem 77