conceputal questions, need help with everything Score: Name: Physics 220Hy by Da
ID: 1777121 • Letter: C
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conceputal questions, need help with everything
Score: Name: Physics 220Hy by David Michaels Angling for a New Idea Conservation of L Moment of Inertia ILL 13 Activity 13.1 Cross Product A) I Spin while holding two dumbbells close to your body with your arms ded, spin around on the rotating chair (be sure your feet are not touching the chair or ground). Next quickly push the dumbbells straight out to arm's-length. When you moved the dumbbells away from your trunk, was there a net torque applied to the system [you + rotating chair + dumbbells]? Explain whether or not and how this accounts for what you observed, by considering changes in the rotational inertia, I B) Torqued by Angular Impulse 1) Hold a fast spinning bike wheel with your feet not touching the chair or ground. With the wheel spinning fast and the axis of rotation vertical, quickly turn it end-over-end once while sitting on an initially stationary stool. Consider you and the stool together to be one part and the bike wheel to be a second part of one physical system. Is the torque you exert on the bike wheel an external or internal torque? the angular momentum of the entire physical system? (If you do this quickly, frictional torques exerted by the wheel-bearings are not significant) What happens to How does the angular momentum of the two individual parts change? momentum vectors for the objects of 'you & stool', the wheel, and the system for the cases 2) Draw angular Conserved System Total SystemExplanation / Answer
A) I spin
when the peson took his arms out, there was no external torque on the system but still the angular velocity of the system reduced. this was because in absence of external torque the angular momentum of the system remains constant. Now when the person pulled out his arms the momnt of inertia of the system increased and to keep the total angular momentum of the system the angular velocity had to reduce.
B) 1. the torque exerted on the bike wheel is internal torque when considering person + chair + wheel as a system
hence the entire physical system has no external torque and hence its total angular momentum has to remain the same
2. angular momentum of the bike wheel is intiall pointing upwards and other parths of the system have no final angular momentum
angular momentum of the bike wheel inverts its direction after it is inverted, so its angular momentum changes, whereas the chair and the person and the bike tire gain additional angular momentum ( lost from the bike wheel) in upward direction to keep thte total value of angular momentum constant with its direction still pointing upwards
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