Question

A cylinder has inner and outer radii of `2 cm` and `3 cm`, respectively, and a mass of `1 kg`. If the cylinder's frequency of counterclockwise rotation about its center changes from `6 Hz` to `12 Hz`, by how much does its angular momentum change?

Answer 1

The change in angular momentum is `=0.0245kgm^2s^(-1)`

Explanation:

The angular momentum is `L=Iomega`

where `I` is the moment of inertia

and `omega` is the angular velocity

The change in angular momentum is

`Delta L=I Delta omega`

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

So, `I=1*(0.02^2+0.03^2)/2=0.00065kgm^2`

`Delta omega =(12-6)*2pi rads^-1`

`Delta L=0.00065*12pi=0.0245kgm^2s^(-1)`