Question

A cylinder has inner and outer radii of `9 cm` and `16 cm`, respectively, and a mass of `4 kg`. If the cylinder's frequency of counterclockwise rotation about its center changes from `10 Hz` to `15 Hz`, by how much does its angular momentum change?

Answer 1

The change in angular momentum is `=2.122.12kgm^2s^(-1)`

Explanation:

The angular momentum is `L=Iomega`

where `I` is the moment of inertia

The change in angular momentum is

`Delta L=I*Delta omega`

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

`Delta omega =(15-10)*2pi=(10 pi )rads^-1`

So, `I=4*(0.09^2+0.16^2)/2=0.0674kgm^2`

`L=10pi*0.0674=2.12kgm^2s^(-1)`