A solid disk, spinning counter-clockwise, has a mass of #4 kg# and a radius of #3/2 m#. If a point on the edge of the disk is moving at #5/7 m/s# in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

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Answer 1 · 2017-02-09T12:55:08

The angular momentum is #=13.5 kgms^(-1)#
The angular velocity is #=2.99 rads^-1#

The angular velocity is

#omega=v/r#

where,

#v=5/7ms^(-1)#

#r=3/2m#

So,

#omega=5/7/3/2*2pi=20/21pi=2.99 rads^-1#

The angular momentum is #L=Iomega#

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

So, #I=4*(3/2)^2/2=9/2kgm^2#

#L=2.99*9/2=13.5 kgms^(-1)#