Calculating Angular Momentum: Mass, Radius, and Frequency Considerations

[jmb07]

A turntable has mass 4.96 kg and a radius of 0.092 m and is spinning with a frequency of 0.53 rev/s. What is the angular momentum??

As simple as this problem seems, I just cannot seem to get the correct answer...here is what i have so far:

I (for a disc) = (1/2)(mr^2)
L = I(omega)
I also know that angular momentum = frequency x I

So,
0.53rev/s(.5 x 4.96kg x 0.092^2) = 0.011 (kgm^2)/s
However the correct answer is 0.0699...what am i doing wrong?

 

[Doc Al]

L = I(omega)
I also know that angular momentum = frequency x I

L = Iω, where ω is in radians/sec.

So,
0.53rev/s(.5 x 4.96kg x 0.092^2) = 0.011 (kgm^2)/s
However the correct answer is 0.0699...what am i doing wrong?

Convert to proper units.

 

[diazona]

The frequency is in revolutions per second; you need to convert it into radians per second. The conversion factor is 2\pi\ \text{radians} = 1\ \text{revolution}.

 

[jmb07]

thanks!