779_Physics ProblemsTechnical Physics

# 779_Physics ProblemsTechnical Physics - dryer is ∆ t =...

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Chapter 27 119 P27.51 At operating temperature, (a) P == = IV 153 120 184 . A V W a fa f (b) Use the change in resistance to find the final operating temperature of the toaster. RR T =+ 0 1 α a f 120 153 120 180 10 4 0 01 0 3 .. . =+× ej T T 441 C T + ° = ° 20 0 441 461 .C C C *P27.52 You pay the electric company for energy transferred in the amount Et = P (a) P t = H G K J F H G I K J F H G I K J = 40 2 86 400 1 48 4 W w e e k s 7 d 1 week s 1 d J 1 W s MJ af . P P t = F H G I K J F H G I K J F H G I K J = = F H G I K J F H G I K J F H G I K J F H G I K J = 40 2 24 1000 13 4 40 2 24 1000 012 61 W w e e k s 7 d 1 week h 1 d k kWh W w e e k s 7 d 1 week h 1 d k \$ kWh a af . . \$1. (b) P t = F H G I K J F H G I K J F H G I K J == 970 3 1000 012 005 82 0 582¢ W m i n 1 h 60 min k kWh a f . \$0. . (c) P t = F H G I K J F H G I K J F H G I K J = 5200 40 ±min 1000 012 416 W 1 h 60 min
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Unformatted text preview: dryer is ∆ t = ≈ × × F H G I K J ≈ 400 600 365 9 10 1 20 7 J s s d d J kWh 3.6 10 J kWh 6 b g b g a f . We suppose that electrically transmitted energy costs on the order of ten cents per kilowatt-hour. Then the cost of using the dryer for a year is on the order of Cost ≅ = 20 10 kWh kWh a fb g \$0. \$2 ~\$1 ....
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