Question

A cylinder has inner and outer radii of `2 cm` and `5 cm`, respectively, and a mass of `12 kg`. If the cylinder's frequency of counterclockwise rotation about its center changes from `6 Hz` to `4 Hz`, by how much does its angular momentum change?

Answer 1

The change in angular momentum is `=0.22kgm^2s^-1`

Explanation:

The angular momentum is `L=Iomega`

where `I` is the moment of inertia

The mass, `m=12kg`

For a cylinder, `I=m((r_1^2+r_2^2))/2`

So, `I=12*((0.02^2+0.05^2))/2=0.0174kgm^2`

The change in angular momentum is

`DeltaL=IDelta omega`

The change in angular velocity is

`Delta omega=(6-4)*2pi=(4pi)rads^-1`

The change in angular momentum is

`DeltaL=0.0174*4pi=0.22kgm^2s^-1`