SOLUTION: The electrical resistance R of a wire varies directly as its length L and inversly as the square of its diameter. A wire 20 meters long and 0.6 centimeters in diameter made from a

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: The electrical resistance R of a wire varies directly as its length L and inversly as the square of its diameter. A wire 20 meters long and 0.6 centimeters in diameter made from a       Log On


   

Question 98957: The electrical resistance R of a wire varies directly as its length L and inversly as the square of its diameter. A wire 20 meters long and 0.6 centimeters in diameter made from a certain alloy has a resistance of 36 ohms. What is the resistance of a piece of wire 60 meters long and 1.2 centimeters in diameter made from the same material.
Answer by stanbon(75887) About Me  (Show Source):
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The electrical resistance R of a wire varies directly as its length L and inversely as the square of its diameter. A wire 20 meters long and 0.6 centimeters in diameter made from a certain alloy has a resistance of 36 ohms. What is the resistance of a piece of wire 60 meters long and 1.2 centimeters in diameter made from the same material.
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R = kL/d^2
36 = k*20/0.6^2
12.96 = 20k
k = 0.648
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EQUATION:
R = (0.648)*L/d^2
R = 0.648*60/1.2^2
R = 27 ohms
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Cheers,
Stan H.