A solid disk, spinning counter-clockwise, has a mass of #12 kg# and a radius of #5/4 m#. If a point on the edge of the disk is moving at #4/3 m/s# in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

1 Answer
Feb 19, 2017

The angular momentum is #=62.8kgm^2s^-1#
The angular velocity is #=6.7rads^-1#

Explanation:

The angular velocity is

#omega=v/r#

where,

#v=4/3ms^(-1)#

#r=5/4m#

So,

#omega=(4/3)/(5/4)*2pi=32/15pi=6.7rads^-1#

The angular momentum is #L=Iomega#

where #I# is the moment of inertia

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

So, #I=12*(5/4)^2/2=75/8kgm^2#

#L=6.7*75/8=62.8kgm^2s^-1#