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 `10 Hz` to `12 Hz`, by how much does its angular momentum change?

Answer 1

The change in angular momentum is `=0.0082kgm^2s^-1`

Explanation:

The angular momentum is `L=Iomega`

where `I` is the moment of inertia

The mass, `m=1kg`

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`

The change in angular momentum is

`DeltaL=IDelta omega`

The change in angular velocity is

`Delta omega=(12-10)*2pi=(4pi)rads^-1`

The change in angular momentum is

`DeltaL=0.00065*4pi=0.0082kgm^2s^-1`