Question

A cylinder has inner and outer radii of `4 cm` and `5 cm`, respectively, and a mass of `6 kg`. If the cylinder's frequency of counterclockwise rotation about its center changes from `7 Hz` to `12 Hz`, by how much does its angular momentum change?

Answer 1

The change in angular momentum is `=0.386kgm^2s^-1`

Explanation:

The angular momentum is `L=Iomega`

where `I` is the moment of inertia

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

So, `I=6*(0.04^2+0.05^2)/2=0.0123kgm^2`

The change in angular momentum is

`DeltaL=IDelta omega`

The change in angular velocity is

`Delta omega=(12-7)*2pi=10pirads^-1`

The change in angular momentum is

`DeltaL=0.0123*10pi=0.386kgm^2s^-1`