341_Physics ProblemsTechnical Physics

341_Physics ProblemsTechnical Physics - Chapter 11 P11.46(a...

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Chapter 11 343 P11.46 (a) The radial coordinate of the sliding mass is rt t a f bg = 00125 . m s . Its angular momentum is Lm r t == 2 2 2 1 20 2 50 2 0 012 5 ωπ .. . kg rev s rad rev m s b g b g b g or Lt 295 10 32 k g m s 23 ej The drive motor must supply torque equal to the rate of change of this angular momentum: τ × = dL dt tt 2 000589 3 kg m s W af (b) f 0 005 89 440 2 59 W s N m (c) P = τω π 0 005 89 5 0 092 5 r a d s W s b g b g (d) f 0 092 5 440 40 7 Ws s W (e) Tm v r mr t t = = 2 2 2 1 20 0 012 5 5 3 70 . kg m s rad s N s b g b g b g (f) Wd t t d t = = zz 0 440 0 440 2 00925 1 2 0 092 5 440 8 96 s s 2 Js s k J . (g) The power the brake injects into the sliding block through the string is b b bb Tv t t dW dt t t d t =⋅= ° = = = =− = − Fv cos . . . . 180 3 70 0 012 5 0 046 3 00463 1 2 0 046 3 440 4 48 0 440 0 440 2 ±Ns ±ms ±Ws s k J s b g b g (h) WWW b =+ = = 896 448 . kJ kJ kJ Just half of the work required to increase the angular momentum goes into rotational kinetic
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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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