A cylinder has inner and outer radii of #2 cm# and #4 cm#, respectively, and a mass of #15 kg#. If the cylinder's frequency of counterclockwise rotation about its center changes from #3 Hz# to #2 Hz#, by how much does its angular momentum change?

1 Answer
Sep 8, 2017

Answer:

The change in angular momentum is #=0.094kgm^2s^-1#

Explanation:

The angular momentum is #L=Iomega#

where #I# is the moment of inertia

The mass of the cylinder is #m=15kg#

The radii of the cylinder are #r_1=0.02m# and #r_2=0.04m#

For the cylinder, the moment of inertia is #I=m(r_1^2+r_2^2)/2#

So, #I=15*(0.02^2+0.04^2)/2=0.015kgm^2#

The change in angular velocity is

#Delta omega=Deltaf*2pi=(3-2)*2pi=2pirads^-1#

The change in angular momentum is

#DeltaL=I Delta omega=0.015*2pi=0.094kgm^2s^-1#