A solid disk, spinning counter-clockwise, has a mass of #15 kg# and a radius of #6 m#. If a point on the edge of the disk is moving at #7 m/s# in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

1 Answer
Mar 26, 2018

The angular momentum is #=315kgm^2s^-1# and the angular velocity is #=1.167rads^-1#

Explanation:

The angular velocity is

#omega=(Deltatheta)/(Deltat)#

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

#omega=v/r#

where,

#v=7ms^(-1)#

#r=6m#

So,

The angular velocity is

#omega=(7)/(6)=1.167rads^-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= 15kg#

So, #I=15*(6)^2/2=270kgm^2#

The angular momentum is

#L=270*1.167=315kgm^2s^-1#