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 `7 Hz`, by how much does its angular momentum change?

Answer 1

The aswer is `=0.15kgms^(-1)`

Explanation:

The angular momentum is `L=Iomega`

where `I` is the moment of inertia

and `omega` is the angular velocity

The change of angular momentum is

`DeltaL=IDelta omega`

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

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

`Delta omega=(7-5)*2pi rads^-1`

`DeltaL=0.012*4pi=0.15kgms^(-1)`