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o-na [289]
3 years ago
7

In old times, before there were train signals, people who worked on the railroad would often put their ear down to the train tra

ck to listen for an oncoming train. Why would this result in hearing the train further off than just listening for the train through the air? Question 3 options: Sound travels slower in air because there are often trees and other items blocking the sound. People did not do this because sound travels faster through less dense material, like air, rather than more dense materiel, like train tracks. Sound travels slower, but louder through solid material because it is more dense, so the train could be heard better this way. Sound waves travel faster in more dense material, and the more dense the material the faster the sound is.
Physics
1 answer:
elena55 [62]3 years ago
8 0
The answer is the second option or B.
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A rectangular block of copper has sides of length 15 cm, 26 cm, and 43 cm. If the block is connected to a 5.0 V source across tw
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Answer:

the case is the one  with the greatest current, L=15 cm ,   i = 2.19 10⁸  A

Explanation:

Ohm's law is

          V = i R

Resistance is

         R = ρ L / A

Where L is the length of the electrons pass and A the area perpendicular to the current

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We can calculate the relationship between the area and the length to know in which direction the maximum currents

Case 1

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Case 2

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Case 3

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        A / L = 0.0907 m

We can see that the case is the one  with the greatest current, L=15 cm

Let's calculate the current

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