A solid disk, spinning counter-clockwise, has a mass of #18 kg# and a radius of #4 m#. If a point on the edge of the disk is moving at #2/3 m/s# in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

1 Answer
Nov 26, 2016

Answer:

The angular momentum is #=24kgm^2s^(-1)#
The angular velocity is #=1/6 Hz#

Explanation:

The angular velocity is #v=r omega#

#v=# velocity #=2/3ms^(-1)#

and #r=#radius #=4m#

So, angular velocity, #omega=v/r=2/3*1/4=1/6 Hz#

The angular momentum is #L=I*omega#

where #I=# moment of inertia

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

where #m=# the mass #=18 kg#

Therefore, #I=18*4*4/2=144 kg m^2#

So, the angular momentum is #L=144*1/6=24kgm^2s^(-1)#