(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A turntable with moment of inertia of 2.0kg*m^2 has a radius of 0.80m and an angular velocity of 1.5 rad/s. A ball is thrown horizontally of 0.4kg at 3.0 m/s and is caught by the turntable by a small and very light cup-shaped mechanism at the turntable's edge. What is the new angular velocity after the ball is caught?

2. Relevant equations

Angular momentum = Moment of Inertia * Angular Velocity

Moment of Inertia of a Disk = (1/2)MR^2

Tangential Velocity = Angular Velocity * Radius

3. The attempt at a solution

Well, I didn't really think the ball had angular velocity since it wasn't rotating so I found the tangential velocity of the turntable and used the moment of inertia to find the mass of the turntable. I then used the Law of Conservation of Momentum to find the tangential velocity of the turntable with the added mass of the ball. This is what I got:

Mass of Turntable * Tangential Velocity + Mass of Ball * Velocity of Ball = (Mass of Turntable + Mass of Ball) * New Velocity

I then solved for the new velocity which I then used to find the new angular velocity. The answer I got (1.6 rad/s) were not one of the choices in the question so I'm assuming I'm wrong.

How can a non-rotating ball have an angular velocity? I'm sure that this is the key somehow.

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# Homework Help: Conservation of Angular Momentum of Turntable Problem

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