A solid disk, spinning counter-clockwise, has a mass of 4 kg and a radius of 3 m. If a point on the edge of the disk is moving at 1/2 m/s in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

1 Answer
Apr 2, 2018

The angular momentum is =3kgm^2s^-1 and the angular velocity is =1/6rads^-1

Explanation:

The angular velocity is

omega=(Deltatheta)/(Deltat)

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

omega=v/r

where,

v=1/2ms^(-1)

r=3m

So,

The angular velocity is

omega=(1/2)/(3)=1/6rads^-1

The angular momentum is L=Iomega

where I is the moment of inertia

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

The mass is m=4 kg

So, I=4*(3)^2/2=18kgm^2

The angular momentum is

L=18*1/6=3kgm^2s^-1