A student sits at rest on a piano stool that can rotate without friction. The mo

Question

A student sits at rest on a piano stool that can rotate without friction. The moment of inertia of the student-stool system is 3.9 kg · m2. A second student tosses a 1.7-kg mass with a speed of 2.7 m/s to the student on the stool, who catches it at a distance of 0.34 m from the axis of rotation. The final angular speed is 0.381 rad/s.
(a) Does the kinetic energy of the mass-student-stool system increase, decrease, or stay the same as the mass is caught?
---Select--- increases decreases stays the same

(b) Calculate the initial and final kinetic energy of the system.
KEi = J
KEf = J

Explanation / Answer

I will treat the tossed mass as a point mass caught exactly perpendicular between the radies and catch point Conservation of angular momentum ?=v/r 2*0.45^2*2.6/0.45=(4.3+2*0.45^2)*? solve for ? ?=(2*0.45^2*2.6/0.45)/(4.3+2*0.45^2) 0.497 rad/s

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