Momentum Not Conserved, in the use of a medieval battle flail

Suddenly I find myself lacking in the motivation to further participate in this debate.

As I have emphasized in the parts of your last post that i've quoted, you're boasting (although I appreciate the compliment in one part of your last post) and trying to cast aspersions over me and what I have said by nitpicking at trivialities in my occasionaly careless use of language.

If you genuinely believe that I have missed something in my summary

of your thought experiment:

Then name it.

If you think I have missed something, then name it.
If you have a question about something I have said, relevant to this quote, ask it.
If not, accept you were wrong, and admit it.
If you do not believe that you were wrong, show me the calculations and equations that demonstrate that I am wrong.
I will no longer be addressing the irrelevant nitpicky trivialities that you are using to distract from the actual discussion at hand.
Such behaviour is stereotypical of someone who knows they are wrong, but can not admit it.

This post has been edited by Trippy on Sep 3 2007, 08:18 PM

Me either.

Can you even write a post that doesn't include insults and negative insinuations?

Indeed, in every post, when Trippy refutes insults and negative insinuations.

And yet you're avoiding my direct questions.

All you need to do is answer the questions I stated in my previous post.

Nothing says you need to rise to what you consider an insult (even if it was what could be considered a statement of fact).

If you think I'm wrong about what I said about your thought experiment, prove it.

That's all I've asked, and thus far, you've been utterly unable to meet that challenge, instead, you seam to be resorting to diversionary tactics and obfuscation, which, in my experience is the tactics of someone who has been shown to be wrong, but is unable to accept it.

Proove me wrong.
Name and equation.
State an energy source I haven't taken into account in addressing your thought experiment.
State somewhere the energy goes that I haven't taken into account.
Show me an energy flux that can not be accounted for.

You can't.
Because you were wrong.

Meanwhile, Zephir provokes, insinuates, quotes out of context, and regularly resorts to lying.

Nothing says you need to rise to what you consider an insult (even if it was what could be considered a statement of fact).

Apparently not.

Gpe.

If the whole system initially consists of two masses, with zero relative momentum, at a distance of asymptotically zero gravity, they have no relative kinetic energy and no gpe.

If you use rockets to accelerate them toward each other, the whole system still has no relative KE since the rocket exhaust represents a negative KE to the masses' now positive KE. However, as they approach each other they develop gpe.

The gpe creates a positive kinetic energy as it accelerates the two masses together.

The gpe came from nothing. It converts to KE and therefore the positive KE came from nothing.

Energy wasn't conserved.

This post has been edited by ubavontuba on Sep 5 2007, 08:13 AM

I suspected you would raise this.

It really is a bit of a straw man, but it's an understandable misconception.

GPE increases to a maximum of Zero (as height increases).

I was sure I mentioned this.

If you're going to use rockets, remember that the fuel contains Chemical Potential energy (CPE).

As Fuel is burned, a force is applied, and work is done, and he body is accelerated.
So, chemical potential energy is turned into kinetic energy.

At all times, GPE + CPE + KE + Heat = Constant.

The gpe is irrelevant to the at rest system. It only becomes relevant to the active system.

Which I accounted for in the exhaust as negative KE.

If you include the exhaust in the system, the KE and the momentum of the system remains unchanged.

Gpe isn't observed in the system until it becomes relevant. It just appears, as if by magic. It induces a KE value that wasn't in the system in the beginning.

This post has been edited by ubavontuba on Sep 6 2007, 04:41 AM

No, you're wrong.
You're blatantly wrong.

GPE is ALWAYS there.

Are you just ignoring the posts where I state that the MAXIMUM GPE an object can have is Zero?

Tell me something.

I have two marbles in a cereal bowl, one marble is in the bottom of the bowl, sitting in the center, the other marble is miraculously precariously perched on the edge of the bowl, which marble do you think has the greatest potential energy?

Hrmmm?

No. I'm not ignoring it.

To clarify, let's say the rockets run just long enough to allow the gravitational bodies to begin attracting.

We can agree that the initial gpe in the system is zero. What happens to the gpe as the masses begin to attract? It attains a negative value.

What happens to gpe after the collision? It disappears! It's zero again!

You're left with only the temperature (which is simply kinetic energy on the molecular and atomic scale). Therefore, the graviatationally induced heat energy essentially just sprang into existence then, right? What is it's source? What is it's symmetry?

Obvously, the one on the edge. However, this is not an isolated system of two masses.

This post has been edited by ubavontuba on Sep 7 2007, 06:28 AM

This is only true at infinity. Since an object at infinity would take an infinite amount of time to reach a finite distance from the gravitating object it never has any GPE with respect to said object (nor any KE). So, energy is conserved.

Which is why I specified "at a distance of asymptotically zero gravity." It's close enough to zero to call it zero.

Besides, "dark energy" (seemingly) observationally contradicts your interpretation.

It also doesn't only have to be considered with the gravitational model. Other isolated potential energy models can be substituted.

This post has been edited by ubavontuba on Sep 7 2007, 07:46 AM

Shemi is right, and yes, you are ignoring it.

First off, no matter how far apart the masses are, there is still some attractive force between them.

Second point. Divide the combined mass up into 1kg blocks.
Calculate the GPE of the 1kg blocks (relative to the center of mass of the system)
Sum them.

Still think it's Zero?

Remember the formula W=f.d?

As the 'falling' mass moves inwards it traverses a distance d.
As the mass moves inwards, and traverses the distance d, a force is applied to it.
Therefore WORK is done on the system.

Still think the Kinetic energy comes from nowhere?

Replace the word "Bowl" with the word "Gravitational well" or "Gravitational field".

Still think my analogy doesn't apply?

See? You're wrong, and I haven't had to apply anything more then highschool physics to prove it, I know you probably think this is an insult, but, it's a statement of fact, and again, I can point you in the direction of the appropriate part of my country's school syllabus to prove it.

And you ignored my points in regards to asymptotically zero, dark energy, and other potential energy models.

In proximity, the lower the mass, the smaller the negative number is. You're also claiming it's always negative at a distance. So therefore I can agree that it's slightly negative at a distance, and slightly negative after combining. They still cancel out!

And the distance of the radius represents only a very small percentage of the total distance the system saw while the masses were falling together. Where'd all that negative gpe energy go? We're left with mostly positive energy!

Yes.

It's not the same. There's an obvious dimensional characteristic that's not apparent in the isolated system. Also, you begin at a point of negative gpe, not zero gpe.

Obviously, yes.

I disagree. You haven't proved anything.

This post has been edited by ubavontuba on Sep 7 2007, 08:50 AM

This 'discussion' is painful, but not the good kind of painful.
It's the bad kind of painful.

I don't know how to say it any simpler.

Mass experiences attractive force.
Mass has large potential to fall.
As mass falls, attractive force makes work on mass.
Work makes POTENTIAL energy KINETIC energy.
When mass hits other energy, under ideal circumstances KINETIC energy is made into PHOTONS
PHOTONS carry away kinetic energy of mass.
At ALL times, the TOTAL energy of the system is constant!

I don't know how to explain it any simpler then that.

And as for my analogy? It's called an analogy for a reason. Most analogies are inherently flawed (much like your deductive reasoning in coming to the conclusion that somehow a meteorite hitting the earth contradicts the known laws of physics).

And as far as the flaws you raised in my model?

1. I define the bowl as being a depression.
2. I define the lip of the bowl as being zero.
3. I define the bottom of the bowl relative to the top of the bowl.
4. I define the 'extra dimensionality' of the system as being representitive of the GPE.

Pifff. Your objections vanish like a puff of smoke on a gust of wind.