Question

A cylinder has inner and outer radii of `4 cm` and `8 cm`, respectively, and a mass of `3 kg`. If the cylinder's frequency of counterclockwise rotation about its center changes from `5 Hz` to `8 Hz`, by how much does its angular momentum change?

Answer 1

The change is `=0.226kgms^(-1)`

Explanation:

The angular momentum is `L=Iomega`

and `DeltaL=IDeltaomega`

where `I` is the moment of inertia

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

So, `I=3/2*(0.04^2+0.08^2)=3/2*0.008=0.012kgm^2`

`DeltaL=0.012*(8-5)*2pi=0.012*3*2pi=0.226kgms^(-1)`