A solid disk, spinning counter-clockwise, has a mass of #3 kg# and a radius of #7/5 m#. If a point on the edge of the disk is moving at #8/3 m/s# in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

1 Answer
Nov 13, 2016

Answer:

The angular momentum is #=28/5kgm^2s^(-1)#
The angular velocity is #=40/12 Hz#

Explanation:

mass #m=3 kg#

radius of solid disc #r=7/5 m#

Velocity on the edge #v=8/3ms^(-1)#

The angular velocity #omega=v/r Hz#

#omega=(8/3)/(7/5)=8/3*5/7=40/21 Hz#

The angular momentum #L=I*omega#

where #I=#moment of inertia

For a solid disc, #I=(mr^2)/2=3*49/25*1/2=147/50kgm^2#

So, angular momentum #L=I*omega=147/50*40/21=28/5kgm^2s^(-1)#