A solid disk, spinning counter-clockwise, has a mass of 5 kg and a radius of 8 m. If a point on the edge of the disk is moving at 6 m/s in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

1 Answer

120\ \text{kgm}^2\text{/s} & 0.75\ \text{rad /s}

Explanation:

Mas of solid disk m=5\ kg

Radius of solid disk r=8\ m

Peripheral speed of disk v=r\omega=6\ m/s

The angular velocity \omega of the disk

\omega=v/r=6/8=0.75\ \text{rad/s}

Mass moment of inertia (I) of solid disk

I=1/2mr^2=1/2(5)(8)^2=160\ kgm^2

Now, the angular momentum J of the solid disk is given as

J=I\omega

=160\cdot 0.75

=120\ \text{kgm}^2\text{/s}