A cylinder has inner and outer radii of 9 cm and 16 cm, respectively, and a mass of 4 kg. If the cylinder's frequency of counterclockwise rotation about its center changes from 9 Hz to 6 Hz, by how much does its angular momentum change?

1 Answer
Feb 5, 2018

The change in angular momentum is =1.27kgm^2s^-1

Explanation:

The angular momentum is L=Iomega

where I is the moment of inertia

and omega is the angular velocity

The mass of the cylinder is m=4kg

The radii of the cylinder are r_1=0.09m and r_2=0.16m

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

So, I=4*((0.09^2+0.16^2))/2=0.0674kgm^2

The change in angular velocity is

Delta omega=Deltaf*2pi=(9-6) xx2pi=pirads^-1

The change in angular momentum is

DeltaL=IDelta omega=0.0674xx6pi=1.27kgm^2s^-1