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In the lab, you have a stool to sit on that spins with negligible friction. A student can sit on the stool with hand weights in her outstretched arms. As she spins, she pulls her arms in close to her body.

What observation do you make and why does this happen?


The student's angular velocity will decrease because her center of mass is more concentrated so the friction for the stool is no longer negligible.


The student will speed up because angular momentum is conserved.


The student will struggle to pull in her arms and very shortly bring them to the outward position again because the centripetal force acting on the weights will pull them outward.


No change is observed because no torque or force is acting on the student.

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