A solid disk, spinning counter-clockwise, has a mass of #14 kg# and a radius of #5/4 m#. If a point on the edge of the disk is moving at #7/9 m/s# in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

1 Answer
Dec 12, 2016

Answer:

The angular momentum is #=170.6 kgm^2s^(-1)#
The angular velocity is #=3.9rads^(-1)#

Explanation:

The angular velocity is #omega#

#omega=v/r=7/9*4/5*2pi rads^(-1)#

#=(56/45pi)rads^(-1)=3.9 rads^(-1)#

The angular momentum is #L=Iomega#

For a solid disc, the moment of inertia #I=1/2mr^2#

#I=1/2*14*25/4=175/4kgm^2#

The angular momentum is

#L=175/4*56/45*pi=170.6 kgm^2s^(-1)#