A cylinder has inner and outer radii of #9 cm# and #14 cm#, respectively, and a mass of #9 kg#. If the cylinder's frequency of counterclockwise rotation about its center changes from #5 Hz# to #7 Hz#, by how much does its angular momentum change?

1 Answer
Aug 15, 2017

Answer:

The change in angular momentum is #=1.57kgms^-1#

Explanation:

The angular momentum is #L=Iomega#

where #I# is the moment of inertia

The mass of the cylinder is #m=9kg#

The radii of the cylinder are #r_1=0.09m# and #r_2=0.14m#

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

So, #I=9*(0.09^2+0.14^2)/2=0.12465kgm^2#

The change in angular velocity is

#Delta omega=Deltaf*2pi=(7-5)*2pi=4pirads^-1#

The change in angular momentum is

#DeltaL=I Delta omega=0.12465*4pi=1.57kgm^2s^-1#