- #1

kmb11132

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## Homework Statement

A CD has a playing time of 59.8 minutes. When the music starts, the CD is rotating at an angular speed of 460 revolutions per minute (rpm). At the end of the music, the CD is rotating at 202 rpm. Find the magnitude of the average angular acceleration of the CD. Express your answer in rad/s^2.

## Homework Equations

angular acceleration = change in angular velocity / change in time

## The Attempt at a Solution

initial angular velocity in rad/s:

460rpm / 60 * 2 * Pi = 48.17rad/s

final angular velocity in rad/s:

202rpm / 60 * 2 * Pi = 21.15rad/s

time in s:

59.8min * 60 = 3588s

angular acceleration:

(21.15 - 48.17) / 3588 = -.00753rad/s^2

I'm really not sure why this is incorrect. I feel like I'm making a really obvious/face-palm type mistake.