A cylinder has inner and outer radii of 2 cm and 3 cm, respectively, and a mass of 1 kg. If the cylinder's frequency of counterclockwise rotation about its center changes from 6 Hz to 2 Hz, by how much does its angular momentum change?

1 Answer
Jan 8, 2018

The change in angular momentum is =0.0163kgm^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=1kg

The radii of the cylinder are r_1=0.02m and r_2=0.03m

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

So, I=1*((0.02^2+0.03^2))/2=0.00065kgm^2

The change in angular velocity is

Delta omega=Deltaf*2pi=(6-2) xx2pi=8pirads^-1

The change in angular momentum is

DeltaL=IDelta omega=0.00065 xx8pi=0.0163kgm^2s^-1