A solid disk, spinning counter-clockwise, has a mass of #8 kg# and a radius of #3/2 m#. If a point on the edge of the disk is moving at #9/8 m/s# in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

1 Answer
Nov 20, 2016

Answer:

The angular momentum is #=27/4kgms^(-1)#
The angular velocity is #=3/4Hz#

Explanation:

The angular velocity #omega# is
#omega=v/r#

where
#v=velocity=9/8ms^(-1)#
#r=radius=3/2m#

so, #omega=9/8*2/3=3/4 Hz#

The angular momentum is

#L=Iomega#

Where #I#=moment of inertia

In the case of a solid disc, #I=(mr^2)/2#

#m=#mass of the disc, #=8kg#

#r=# radius of the disc, #=3/2 m#

Therefore, #I=1/2*8*9/4=9 kgm^2#

The angular momentum is #L=9*3/4=27/4kgms^(-1)#