Question

A cylinder has inner and outer radii of `12 cm` and `18 cm`, respectively, and a mass of `6 kg`. If the cylinder's frequency of rotation about its center changes from `4 Hz` to `8 Hz`, by how much does its angular momentum change?

Answer 1

The change in anglar momentum is `=3.53kgm^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*(0.12^2+0.18^2)/2=0.1404kgm^2`

The change in angular momentum is

`DeltaL=IDelta omega`

`Delta omega=(8-4)*2pi=8pirads^-1`

`DeltaL=0.1404*8pi=3.53kgm^2s^-1`