A solid disk, spinning counter-clockwise, has a mass of #13 kg# and a radius of #8/5 m#. If a point on the edge of the disk is moving at #7/4 m/s# in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

1 Answer
Mar 3, 2018

Answer:

The angular momentum is #=18.2kgm^2s^-1# and the angular velocity is #=1.094rads^-1#

Explanation:

The angular velocity is

#omega=(Deltatheta)/(Deltat)#

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

#omega=v/r#

where,

#v=7/4ms^(-1)#

#r=8/5m#

So,

The angular velocity is

#omega=(7/4)/(8/5)=1.09375rads^-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=13 kg#

So, #I=13*(8/5)^2/2=16.64kgm^2#

The angular momentum is

#L=16.64*1.094=18.2kgm^2s^-1#