Angular Momentum of circular disk

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The discussion centers on calculating the angular momentum and resulting angular speed of a circular disk with a person running on it. The disk has a radius of 2.50 m and a mass of 100 kg, while the person has a mass of 55.0 kg and runs at a speed of 2.20 m/s. The user is struggling to apply the angular motion equations, specifically L = I*omega and I = mr^2, to find the initial angular momentum and angular speed. They are reminded that angular momentum is conserved, prompting them to consider the initial state of the system before the person starts running. The key takeaway is to calculate the initial angular momentum to determine the resulting angular speed.
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Homework Statement


A flat uniform circular disk (radius = 2.50 m, mass = 1.00 102 kg) is initially stationary. The disk is free to rotate in the horizontal plane about a frictionless axis perpendicular to the center of the disk. A 55.0 kg person, standing 1.55 m from the axis, begins to run on the disk in a circular path and has a tangential speed of 2.20 m/s relative to the ground.


Homework Equations



I have been using the definition of angular motion equation (L = I*omega)(I = mr^2) to try and find the resulting angular speed. What I am having trouble with is how to find L using the given numbers. I thought i read that L = r2, but putting those numbers into the equation has not given me the correct answer. The problem asks me to find the resulting angular speed, but since I have not been able to find L or omega, I haven't been able to solve.

Thanks.
 
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Hint: Angular momentum is conserved. What's the initial angular momentum of the system before the person begins running?
 

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