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3 years ago

A 2.0 mm diameter wire of length 20 m has a resistance of 0.25 ȍ. what is the resistivity of the wire?

1 answer:

5 0

The relationship between resistance R and resistivity $\rho$ is
$R= \frac{\rho L}{A}$ (1)
where L is the length of the wire and A is the cross-sectional area.

In our problem, the radius of the wire is half the diameter: r=1 mm=0.001 m, so the cross-sectional area is
$A=\pi r^2 = \pi (0.001 m)^2=3.14 \cdot 10^{-6} m^2$
The length of the wire is L=20 m and the resistance is $R=0.25 \Omega$ .

By re-arranging equation (1), we can find the resistivity of the wire:
$\rho = \frac{RA}{L}= \frac{(0.25 \Omega)(3.14 \cdot 10^{-6} m^2)}{(20 m)} = 3.93 \cdot 10^{-8} \Omega \cdot m$

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3 years ago

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3 years ago

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postnew [5]

Sounds like the situation is modeled like so:

[Light] - - - - - - - - - - [You] => - - -

- - - - - - - - - - - - - - - [Cop] - - - - -

<= = = 200 m = = =>

where your velocity is 27.8 m/s to the right. So the question is asking, is it possible that your car, given that it accelerates at a maximum of 1/5 m/s^2, can reach a speed of 27.8 m/s from rest in the time it takes for it to cover 200 m.

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so that after 16.3 s, your car is moving at a speed of

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4 years ago

Liquid flows through a 4.0 cm diameter pipe at 1.0 m/s. there is a 2.0 cm diameter restriction on the line. what is the velocity

Vanyuwa [196]

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3 years ago