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A student sits in a chair that can spin without friction. The student has her hands...

A student sits in a chair that can spin without friction. The student has her hands outstretched and starts rotating at 1.7 rev/s. Her initial rotational inertia about the central axis is 13.00 kg m2. She pulls her hands inward and decreases her rotational inertial to 7.60 kg m2. What is her resulting angular speed after she pulls her hands inward?(rad/s) (in rad/s)

What is the ratio of the new kinetic energy of the system to the original kinetic energy?  

What provided the added kinetic energy?  
platform
friction
gravity
muscles
brainwaves

Science   Physics   
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