592_Physics ProblemsTechnical Physics

592_Physics ProblemsTechnical Physics - 594 *P20.60 Heat...

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594 Heat and the First Law of Thermodynamics *P20.60 The initial moment of inertia of the disk is 1 2 1 2 1 2 1 2 8 920 28 1 2 1 033 10 222 2 4 10 MR VR R tR == = = × ρρ π kg m m m kg m 32 ej af .. The rotation speeds up as the disk cools off, according to II MR MR MR T T ii f f ff i f fi ωω α ω = = = −× ° ° = 1 2 1 2 1 2 1 1 1 25 1 11 71 0 8 3 0 25 720 7 22 2 2 2 6 2 ch rad s 1C C rad s . (a) The kinetic energy increases by 1 2 1 2 1 2 1 2 1 2 1 2 1 033 10 25 0 720 7 9 31 10 2 10 10 III i i i if i i i i f i ωωω −= =×⋅ = × di bg . kg m rad s rad s J 2 (b) ∆∆ Em c T int kg 387 J kg C C C J × ° ° ° = × 264 10 20 850 847 10 2 (c) As 847 10 12 . × J leaves the fund of internal energy, 931 10 10 . × J changes into extra kinetic energy, and the rest, 838 10 12 . × J is radiated. *P20.61 The loss of mechanical energy is 1 2 1 2 670 667 10 6 57 10 4 20 10 1 08 10 2 2 11 10 10 11 mv GM m R i E E += × + ×× × kg 1.4 10 m s Nm 5.98 10 kg 670 kg kg 6.37 10 m J J 4 4 26 . ... One half becomes extra internal energy in the aluminum:
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This note was uploaded on 12/14/2011 for the course PHY 203 taught by Professor Staff during the Fall '11 term at Indiana State University .

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