A solid disk, spinning counter-clockwise, has a mass of #11 kg# and a radius of #4/7 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 22, 2016

Answer:

The angular velocity is #=7/6Hz#
The angular momentum is #=308/147kgm^2s^(-1)#

Explanation:

The angular velocity is given by the formula #omega=v/r#

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

The radius #r=4/7 m#

So, #omega=(2/3)/(4/7)=2/3*7/4=7/6 Hz#

The angular momentum, #L=Iomega#

where #I=#moment of inertia

For a solid disc,

#I=(mr^2)/2#

#I=1/2*11*(4/7)^2=(11*8)/(49)=88/49kgm^2#

So,

#L=88/49*7/6=308/147kgm^2s^(-1)#