The resistance R of wire varies directly as its length L and inversely as the square of its diameter d

a.write an equation that express this joint variation (use k for the constant proportionality)
B.find the constant of proportionality if a wire 1.8m long and 0.005m in diameter has a resistance of 190ohms (round your answer to six decimal places)k=?
C.Find the resistance of a wire made of the same material that is 4m long and has a diameter of 0.009m (round your answer to the nearest whole number) R=? In ohms
D.if the diameter is doubled and the length is tripled by what factor is the resistance changed?

5 answers

a. The equation that expresses this joint variation is: R = k * (L / d^2)

b. To find the constant of proportionality, we can plug in the given values into the equation and solve for k:
190 = k * (1.8 / 0.005^2)
190 = k * (1.8 / 0.000025)
k = 190 / (1.8 / 0.000025)
k ≈ 2,638,888.888889 (rounded to six decimal places)

c. To find the resistance, we can plug in the given values into the equation:
R = k * (4 / 0.009^2)
R = 2,638,888.888889 * (4 / 0.000081)
R = 2,638,888.888889 * 49,382.716049
R ≈ 130,304,249,382.716 (rounded to the nearest whole number)
The resistance is approximately 130,304,249,383 ohms.

d. When the diameter is doubled and the length is tripled, the new equation for resistance becomes:
R' = k * ((3L) / (2d)^2)

The factor by which the resistance is changed can be found by comparing R' to the original resistance R:
(R') / R = (k * ((3L) / (2d)^2)) / (k * (L / d^2))
(R') / R = ((3L) / (2d)^2) / (L / d^2)
(R') / R = (3L * d^2) / (2d)^2
(R') / R = (3L * d^2) / 4d^2
(R') / R = 3L / 4d^2
(R') / R = (3/4) * (L / d^2)

Therefore, the resistance is changed by a factor of 3/4.
Translate the following to spanish:

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Translate the following to spanish:

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