Physics drwls please help
posted by Mary on .
A certain CD has a playing time of 80 minutes. When the music starts, the CD is rotating at an angular speed of 4.8 x 10^2 revolutions per minute (rpm). At the end of the music, the CD is rotating at 2.1 x 10^2 rpm. Find the magnitude of the average angular acceleration of the CD. Express your answer in rad/s2.
(0.104667 x 2.7) / (80 x 60)=
0.000058875
[270 rev/min* 2 pi rad/rev* 1/60 min/sec]/(4800 sec) = 5.89*10^3 rad/sec^2
You forgot the 10^2 multiplier on the rpms.
drwls the system is telling me the answer is incorrect. I saw where my I made the mistake and corrected it but it is still wrong. The answer I came up with is 0.00589 rad/sec^2.
You are right about the minus sign, since it is decelerating. Maybe they want you to use only two significant figures (5.9*10^3). Other than that, I don't see why it is getting marked wrong.

I had this prob with different numbers. it wants the answer in scientific notation. mine was 6.5E3