Let\'s begin with the angular acceleration of a compact disk (CD). To play music

Question

Let's begin with the angular acceleration of a compact disk (CD). To play music the CD must rotate at high speed while a laser reads data encoded in a spiral pattern on the disk. The disc has radius R=6.0cm=0.060m; when data are being read, it spins at 7200 rev/min.

An old-fashioned vinyl record is designed to turn at 33 rev/min, average angular velocity is 3.5 rad/s

Question: Find the angular acceleration of the record if it spins through four full rotations before coming to a stop when the record player is turned off.

Answers tried .24, -.24 and -2.54

Explanation / Answer

from the kinematic equations

wf^2 = wi^2-2*alpha*theta

wf = 0

wi = 33 rev/min = 33*2pi/60 rad/sec

theta = 4*2pi rad

alpha = ?

33*2pi/60 = 2*alpha*4*2pi

alpha = 33/60*8

alpha = 0.069 rad/s^2

Related Questions

Navigate

• Browse (All)
• Browse L
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.