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1. The problem statement, all variables and given/known data

A 190 kg woman stands at the rim of a horizontal turntable with a moment of inertia of 1.3x10^3 kg.m^2 and a radius of 0.68 m. The system is initially at rest and the turntable is free to rotate about a frictionless vertical axle through its center. The woman then starts walking clockwise (when viewed from above) around the rim at a constant speed of 0.86 rad/s relative to the Earth.

With what angular speed does the turntable rotate? Answer in units of rad/s.

2. Relevant equations

w(angular velocity)=v/r

I=mr^2

Conservation of angular momentum I(woman)W(woman)=I(turntable)W(turntable)

3. The attempt at a solution

FIRST, I figured out the angular velocity of the woman.

w=v/r=0.86/0.68=1.2647 m/s

SECOND, I figured out the moment of inertia of the woman.

I=mr^2=(190)(0.68^2)=87.856

LAST, I used this information to solve for the angular speed of the turntable using the Conservation of Angular Momentum equation.

I(woman)W(woman)=I(turntable)W(turntable)

Rearranging this equation, I get W(turntable)=I(woman)W(woman)/I(turntable)

W(turntable)=(87.856x1.2647)/(1.3x10^3)

W(turntable)=0.08547

However, when I punch this answer in, it says the answer is wrong but I don't know what I'm doing wrong. HELP!!!

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# Rotational kinematics and energy

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