Question

A cylinder has inner and outer radii of `16 cm` and `24 cm`, respectively, and a mass of `3 kg`. If the cylinder's frequency of rotation about its center changes from `5 Hz` to `2 Hz`, by how much does its angular momentum change?

Answer 1

The change in angular momentum is `=2.35kgm^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=3*(0.16^2+0.24^2)/2=0.1248kgm^2`

The change in angular momentum is

`DeltaL=IDelta omega`

`Delta omega=(5-2)*2pi=6pi`

`DeltaL=0.1248*6pi=2.35kgm^2s^-1`