# Either I can't do Pythagoreas or this book can't

• flyingpig
In summary: I would say that it has more features. Once again: it's free. That means that you can download it and try it out. If you don't like it, you can just uninstall it.

## Homework Statement

http://www.students.uidaho.edu/documents/HW02%20with%20solutions.pdf?pid=102870&doc=1 [Broken]

Go to question 19.

How in the world is it R^2 - d^2?

Also, when they say the flux is 0 for same amount that enters and exits, why isn't it the same case for R>d?

[PLAIN]http://img406.imageshack.us/img406/590/68326652.png [Broken]

Look at picture, is it because the E field is only going out and nothing is really "going in" that for R>d, it isn't 0?

## The Attempt at a Solution

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flyingpig said:
Look at picture, is it because the E field is only going out and nothing is really "going in" that for R>d, it isn't 0?

Yeah. For there to be a net flux through the surface, there has to be a "source" or a "sink" for field lines (a place where they diverge from or converge to). That's precisely what electric charges are. In the absence such a source or a sink, there is no NET flux through the surface, because any field line that enters from the outside ends up passing out again.

cepheid said:
Yeah. For there to be a net flux through the surface, there has to be a "source" or a "sink" for field lines (a place where they diverge from or converge to). That's precisely what electric charges are. In the absence such a source or a sink, there is no NET flux through the surface, because any field line that enters from the outside ends up passing out again.

But isn't that what my drawing is? While the charge is inside, the amount that is inside is also the amount that is leaving

flyingpig said:
But isn't that what my drawing is? While the charge is inside, the amount that is inside is also the amount that is leaving

Yes, I am not disagreeing with you. I was saying that there would be no net flux if there were NO charges enclosed (as would be the case for R < d). But in the case of your diagram, since R > d, there IS charge enclosed, and these sources of field lines within the surface lead to a net outward flux through that surface.

By the way, look at the diagram below: can you do Pythagoras on either one of the two identical right triangles shown in order to solve for x?

http://img829.imageshack.us/img829/3406/linecharge.th.png [Broken]

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cepheid said:
Yes, I am not disagreeing with you. I was saying that there would be no net flux if there were NO charges enclosed (as would be the case for R < d). But in the case of your diagram, since R > d, there IS charge enclosed, and these sources of field lines within the surface lead to a net outward flux through that surface.

By the way, look at the diagram below: can you do Pythagoras on either one of the two identical right triangles shown in order to solve for x?

http://img829.imageshack.us/img829/3406/linecharge.th.png [Broken]

Ohhh okay, thank you, that was amazing!

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By the way, did you use Paint to draw this? Because that's what I use...

flyingpig said:
By the way, did you use Paint to draw this? Because that's what I use...

No, I used the drawing program that comes with OpenOffice. OpenOffice is a suite of software that includes word processing, spreadsheet, and presentation-making programs. So, it's just like Microsoft Office, except that it is free and open source.

cepheid said:
No, I used the drawing program that comes with OpenOffice. OpenOffice is a suite of software that includes word processing, spreadsheet, and presentation-making programs. So, it's just like Microsoft Office, except that it is free and open source.

Do you need to purchase an electronic pen to do that?

flyingpig said:
Do you need to purchase an electronic pen to do that?

No, the drawing program works like Paint. You use the mouse to draw shapes, etc.

cepheid said:
No, the drawing program works like Paint. You use the mouse to draw shapes, etc.

Is it better than Paint...?

flyingpig said:
Is it better than Paint...?

I would say that it has more features. Once again: it's free. That means that you can download it and try it out. If you don't like it, you can just uninstall it.

## 1. What is Pythagorean theorem and why is it important?

Pythagorean theorem is a mathematical principle that states that in a right triangle, the square of the length of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the other two sides. It is important because it allows us to find the missing side length in a right triangle and has many real-world applications in fields such as architecture, engineering, and physics.

## 2. Why do some people struggle with understanding Pythagorean theorem?

Many people struggle with understanding Pythagorean theorem because it involves the use of abstract concepts and algebraic equations. It also requires a strong understanding of basic geometry and trigonometry, which can be challenging for some individuals.

## 3. Can you explain Pythagorean theorem in simpler terms?

Pythagorean theorem can be explained as the relationship between the sides of a right triangle. It tells us that the sum of the squares of the two shorter sides is equal to the square of the longest side (hypotenuse).

## 4. How is Pythagorean theorem used in real life?

Pythagorean theorem has many practical applications in everyday life. For example, it is used in construction to ensure that buildings are built with right angles, in navigation to determine distances, and in sports to calculate the distance between two points on a field or court.

## 5. Are there any other theorems similar to Pythagorean theorem?

Yes, there are many other theorems that are based on or related to Pythagorean theorem, such as the Law of Cosines and the Law of Sines. These theorems are also used in trigonometry and have real-world applications in fields such as surveying and navigation.