Question

A solid disk, spinning counter-clockwise, has a mass of `6 kg` and a radius of `2 m`. If a point on the edge of the disk is moving at `5/2 m/s` in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

Answer 1

`omega = 1.25 (radians/s)` and `L = 15 (kg*m^2)/s`

Explanation:

The relationship between instantaneous velocity, v and angular velocity, `omega`, is
`omega = v/r`

So `omega = (5/2 m/s)/(2 m) = 1.25 (radians)/s`

Angular momentum is `I*omega` where
`I = (M*R^2)/2`

So, the angular momentum, `L`, is
`L = (6 kg*(2 m)^2)/2*1.25 (radians)/s = 15 (kg*m^2)/s`

I hope this helps,
Steve