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- Thread starter kthouz
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Perfectly elastic collisions exist, but not with macroscopic objects. There is always some energy lost to noise and heat. But at particle level (molecules, atoms, electrons, etc.) most of the collisions are perfectly elastic.

- #3

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How to find mathematically that a force is conservetive? i know by definition that a conservative force is a force in which work done is indipendent of the path followed like gravitational force.

- #4

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if we know the function of the force , and [tex]\nabla \times F=0[/tex]

then it is conservetive

then it is conservetive

- #5

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but i dont know, kthouz,whether you are a college student.

if not, just remember the friction isn't

if not, just remember the friction isn't

- #6

George Jones

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What aboutif we know the function of the force , and [tex]\nabla \times F=0[/tex]

then it is conservetive

[tex]F \left( x , y , z \right) = \frac{-y}{x^2 + y^2} \hat{x} + \frac{x}{x^2 + y^2} \hat{y}?[/tex]

:uhh:

- #7

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What about [tex] x=y=0[/tex]?What about

[tex]F \left( x , y , z \right) = \frac{-y}{x^2 + y^2} \hat{x} + \frac{x}{x^2 + y^2} \hat{y}?[/tex]

:uhh:

[tex]\nabla\times F= 0[/tex] except for [tex] x=y=0[/tex]

The function has a discontinuity for [tex] x=y=0,\,\,\, F=\infty[/tex]

For any closed path that does not enclose the origin, any line integral of the function is zero.

Happily, in physics you don't often find functions with poles.

Anyhow, I don't think that this thread is the good one to talk about curls and discontinuities.

It is better to stick to the original question and to the level of the question. Talk about curls to someone who asks about elastic collisions is not a good idea. There are other ways to explain what is a conservative force.

- #8

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alright,alright, so talk about how to explain conservetive force mathematically

without curls.

without curls.

- #9

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I can assure you that,

A conservative force is a force whose exerted work is converted in potential energy which can be transformed back completely into mechanical work.

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