A solid disk, spinning counter-clockwise, has a mass of 8 kg and a radius of 3/2 m. If a point on the edge of the disk is moving at 9/8 m/s in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

1 Answer
Nov 20, 2016

The angular momentum is =27/4kgms^(-1)
The angular velocity is =3/4Hz

Explanation:

The angular velocity omega is
omega=v/r

where
v=velocity=9/8ms^(-1)
r=radius=3/2m

so, omega=9/8*2/3=3/4 Hz

The angular momentum is

L=Iomega

Where I=moment of inertia

In the case of a solid disc, I=(mr^2)/2

m=mass of the disc, =8kg

r= radius of the disc, =3/2 m

Therefore, I=1/2*8*9/4=9 kgm^2

The angular momentum is L=9*3/4=27/4kgms^(-1)