A solid disk, spinning counter-clockwise, has a mass of 11kg and a radius of 47m. If a point on the edge of the disk is moving at 85ms in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

1 Answer
Dec 26, 2016

The angular momentum of the disk is 5 kgm2s and the angular velocity is 145rads(2.8rads).

Explanation:

Angular momentum is given by L=Iω, where I is the moment of inertia of the object, and ω is the angular velocity of the object.

The moment of inertia of a solid disk is given by I=12mr2, and angular velocity is given by vr, where v is the tangential velocity and r is the radius.

We are given that m=11kg, r=47m, and v=85ms. We can use these values to calculate the moment of inertia and angular velocity, and ultimately the angular momentum.

ω=vr=85ms47m

ω=145rads

This is the angular velocity.

I=12mr2=12(11kg)(47m)2

I=8849kgm2

This is the moment of inertia.

We can now calculate the angular momentum:

L=Iω=(8849kgm2)(145rads)

L=17635kgm2s

L5kgm2s