Audio CD players read the data on the disc at a constant tangential speed and th
ID: 1635176 • Letter: A
Question
Audio CD players read the data on the disc at a constant tangential speed and thus must vary the disc's angular speed as the reading position moves from the inner edge to the outer edge. The radius of the innermost track is 25 mm and the rotational speed of the disk when the innermost track is read is 8 revolutions per second. What is the required angular speed (in rad/s) of the disk when the outermost track, whose radius is 58 mm, is read at the same rate as the innermost track? 18.7 21. 24.7 28.7 You decide to stop listening to the music when the angular speed is 40 rad/s, and the disk stops after 11 complete revolutions. What is the magnitude of the average angular acceleration in (rad/s)? 11.6 7.6 9.7 13.0Explanation / Answer
12) Since tangential speed is constant,
1r1 = 2r2
=> 2 = 1r1/r2 = (8 * 2) * 25 / 58 = 21.7 rad/s
13) Average angular acceleration, = 2/2 = 402 / (2 * 11 * 2) = 11.6 rad/s2
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