A solid disk, spinning counter-clockwise, has a mass of 18 kg and a radius of 9/4 m. If a point on the edge of the disk is moving at 7/3 m/s in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

1 Answer
Mar 22, 2017

The angular momentum is =47.25kgm^2s^-1
The angular velocity is =1.037rads^-1

Explanation:

The angular velocity is

omega=(Deltatheta)/(Deltat)

v=r*((Deltatheta)/(Deltat))=r omega

omega=v/r

where,

v=7/3ms^(-1)

r=9/4m

So,

omega=(7/3)/(9/4)=28/27=1.037rads^-1

The angular momentum is L=Iomega

where I is the moment of inertia

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

So, I=18*(9/4)^2/2=729/16kgm^2

L=729/16*1.037=47.25kgm^2s^-1