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

Answer:

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#