# Thread: Angular velocity of a platform

1. ## Angular velocity of a platform

I don't know the idea.
I can find momentum of inertia of disc-shaped platform but don't know how to link it with mass of a man who walks on the disc-shaped platform.
This excercises seems to be based on momentum of impulse of conservation law

2. Originally Posted by totalnewbie
I don't know the idea.
I can find momentum of inertia of disc-shaped platform but don't know how to link it with mass of a man who walks on the disc-shaped platform.
This excercises seems to be based on momentum of impulse of conservation law

Angular momentum of the platform is $\displaystyle |I \omega|=|m\, v\, r|$ , where $\displaystyle m$ is the mass of the man $\displaystyle v$ his speed, $\displaystyle r$ the radius of the platform $\displaystyle I$ the moment of inertia of the platform and $\displaystyle \omega$ the angular velocity of the platform (the platform rotates in the opposite direction to that in which the man walks.