A solid disk, spinning counter-clockwise, has a mass of #16 kg# and a radius of #3/7 m#. If a point on the edge of the disk is moving at #8/5 m/s# in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

1 Answer
Apr 19, 2017

Answer:

The angular momentum is #=381.95kgm^2s^-1#
The angular velocity is #=3.73rads^-1#

Explanation:

The angular velocity is

#omega=(Deltatheta)/(Deltat)#

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

#omega=v/r#

where,

#v=8/5ms^(-1)#

#r=3/7m#

So,

#omega=(8/5)/(3/7)=56/15=3.73rads^-1#

The angular momentum is #L=Iomega#

where #I# is the moment of inertia

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

So, #I=16*(8/5)^2/2=512/25=102.4kgm^2#

The angular momentum is

#L=102.4*3.73=381.95kgm^2s^-1#