A solid disk, spinning counter-clockwise, has a mass of #9 kg# and a radius of #4 m#. If a point on the edge of the disk is moving at #12 m/s# in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

1 Answer
Jan 11, 2018

Answer:

The angular momentum is#=216kgm^2s^-1# and the angular velocity is #=3rads^-1#

Explanation:

The angular velocity is

#omega=(Deltatheta)/(Deltat)#

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

#omega=v/r#

where,

#v=12ms^(-1)#

#r=4m#

So,

The angular velocity is

#omega=(12)/(4)=3rads^-1#

The angular momentum is #L=Iomega#

where #I# is the moment of inertia

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

The mass is #m=9 kg#

So, #I=9*(4)^2/2=72kgm^2#

The angular momentum is

#L=72*3=216kgm^2s^-1#