Question

A solid disk, spinning counter-clockwise, has a mass of `1 kg` and a radius of `7 m`. If a point on the edge of the disk is moving at `3 m/s` in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

Answer 1

The angular momentum is `=66kgm^2s^-1`
The angular velocity is `=2.69rads^-1`

Explanation:

The angular velocity is

`omega=v/r`

where,

`v=3ms^(-1)`

`r=7m`

So,

`omega=(3)/(7)*2pi=6/7pi=2.69rads^-1`

The angular momentum is `L=Iomega`

where `I` is the moment of inertia

For a solid disc, `I=(mr^2)/2`

So, `I=1*(7)^2/2=49/2kgm^2`

The angular momentum is

`L=2.69*49/2=66kgm^2s^-1`