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| 183_notes:examples:rotational_kinetic_energy_and_work [2014/11/05 21:33] – pwirving | 183_notes:examples:rotational_kinetic_energy_and_work [2014/11/14 07:01] (current) – pwirving | ||
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| - | ===== Example: | + | ===== Example: |
| In the figure which is in the representations section you observe that a wheel is mounted on a stationary axel, which is nearly frictionless so that the wheel turns freely. The wheel has an inner ring with mass 5 kg and radius 10 cm and an outer ring with mass 2 kg and radius 25 cm; the spokes have negligible mass. A string with negligible mass is wrapped around the outer ring and you pull on it, increasing the rotational speed of the wheel. During the time that the wheel' | In the figure which is in the representations section you observe that a wheel is mounted on a stationary axel, which is nearly frictionless so that the wheel turns freely. The wheel has an inner ring with mass 5 kg and radius 10 cm and an outer ring with mass 2 kg and radius 25 cm; the spokes have negligible mass. A string with negligible mass is wrapped around the outer ring and you pull on it, increasing the rotational speed of the wheel. During the time that the wheel' | ||
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| You, the Earth, and the axle will exert forces on the system. How much work does the Earth do? Zero, because the center of mass of the wheel doesn' | You, the Earth, and the axle will exert forces on the system. How much work does the Earth do? Zero, because the center of mass of the wheel doesn' | ||
| - | $W = \frac{1}{2}(0.175 kg \cdot m^{2})(44.0^2 | + | $W = \frac{1}{2}(0.175 kg \cdot m^{2})(44.0^2 |