Question

A cylinder has inner and outer radii of `8 cm` and `18 cm`, respectively, and a mass of `1 kg`. If the cylinder's frequency of counterclockwise rotation about its center changes from `15 Hz` to `9 Hz`, by how much does its angular momentum change?

Answer 1

The change in angular momentum is `=1.46kgm^2s^-1`

Explanation:

The angular momentum is `L=Iomega`

where `I` is the moment of inertia

Mass, `m=1kg`

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

So, `I=1*((0.08^2+0.18^2))/2=0.0388kgm^2`

The change in angular momentum is

`DeltaL=IDelta omega`

The change in angular velocity is

`Delta omega=(15-9)*2pi=(12pi)rads^-1`

The change in angular momentum is

`DeltaL=0.0388*12pi=1.46kgm^2s^-1`