A solid disk, spinning counter-clockwise, has a mass of 6 kg and a radius of 3/5 m. If a point on the edge of the disk is moving at 5/6 m/s in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

1 Answer
Apr 7, 2017

The angular momentum is =1.5kgm^2s^-1
The angular velocity is =1.39rads^-1

Explanation:

The angular velocity is

omega=(Deltatheta)/(Deltat)

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

omega=v/r

where,

v=5/6ms^(-1)

r=3/5m

So,

omega=(5/6)/(3/5)=25/18=1.39rads^-1

The angular momentum is L=Iomega

where I is the moment of inertia

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

So, I=6*(3/5)^2/2=27/25kgm^2

The angular momentum is

L=27/25*25/18=1.5kgm^2s^-1