Extended trolling, which I nevertheless felt obliged to counter.



(In the following, I assume that when you say 'is', you mean what I do when I say 'exerts' below).

Seriously, look up what you're talking about. You are very very wrong, and clearly have no idea of the physics behind these things.

You can't say 'gravity isn't a force because it does not have an exchange particle', because this has no bearing on what a force is. Gravity does exert a force, of magnitude GmM/r^2, and can be measured quite easily. This force causes an acceleration, exactly as basic physics predicts.

What gravity is is a separate question, and has no bearing on the fact that it exerts a force by any standard definition. It turns out that modelling it as a curvature of space-time works extremely well, though. This model has gravity exert a force...which works fine with classical mechanics.

Back on the topic of exchange particles, it isn't obvious that gravity doesn't have one. You can look up 'graviton' on wikipedia for more information, though the ideas behind this are relatively advanced quantum mechanics. On the other hand, it may not have one...this is an unsolved question in quantum mechanics.

I have no idea what you think a 'magnetron' is.



I...don't know how to tell you you're wrong any better than various people already have. What is observed is precisely what is predicted by standard classical mechanics.

During freefall, every part of the spring is acted upon by gravity in the same way. In the spring's reference frame, the only force upon is the internal force causing it to pull together, so it does.

It is not true that all other examples of force cause the spring to stay stretched. It is perhaps true that all the examples you have considered cause it to stay stretched (I haven't thought about it), but this would probably be because you are pulling the end of the spring rather than exerting an equal force upon every atom (as gravity does). This is a fairly fundamental difference in the mechanics.

OK. I'm calling science troll on this discussion. Phillip1882, I'm sorry if you are actually believing this train of thought you've been describing, but as has been stated earlier, you don't really seem to even have the terminology down to try to explain/defend these theories much less a solid rebuttal for hundreds of years of classical mechanics. And if you really need to actually pull a spring across a table to see what'll happen, I'd suggest spending some more time working with thought experiments before demanding justification for how things fall. Again, sorry if these are your actual beliefs, but based on what I've seen so far if everyone is being honest I don't think any minds are going to be changed or convinced here.

On a lighter note, here is my favorite science debunking/explanation in quite a while:



Copyright Darby Conley 2010

Bruce "I have a degree. In Science!" Young

_________________
Currently reading: Plutarch, Cerebus, and D&Q 25th Anniversary

Phillip -- if I tied a rope around your neck and started accelerating your body at 9.8 m/s^2, what do you think would happen?

Have you ever dived head-first off a diving board? What happened?

Do you see what I'm driving at? I think this is more evidence for our theory.

seriously not trying to troll guys, I'm just trying to debate in a logical manner.

can you give me an example of a force that wouldn't cause the spring to stretch?

I'll go ahead and end my argument here, as it's clear to me at least we've hit an impasse, i won't convince you, you won't convince me, so let's just stop.

It isn't a matter of 'a force', it's a matter of where the force is exerted.

If this spring is at equilibrium, and you drop it, it will remain at equilibrium because gravity exerts an equal force on every atom, so they all accelerate in exactly the same way. This means there is no relative motion between the atoms, so the spring does not extend or contract.

If the spring is not at equilibrium, and you drop it, it will oscillate. This is because gravity again acts on every atom in the same way, which means there is no relative force upon the atoms in the spring's rest frame. The only forces in that frame are those pushing it towards equilibrium (from its own extension), so it extends/contracts as appropriate, and oscillates.

What part of this do you have a problem with?

Edit: You also still haven't coherently explained your problem with conventional classical mechanics, or in any way justified your incorrect use of the word 'force'.

So what if we substitute gravity with any other force?

Imagine a massless powerful magnetic field out in space, with no gravity, that accelerates your system toward it at a rate of 9.81 m/s/s. You hold your system in place, so that that ball is accelerated toward the magnetic field, until the forces of magnetism, the spring force, and your hand balance out. You then release the spring system toward the magnetic field in space. The spring and ball will still oscillate while accelerating toward the magnetic field.

You can replace this with any other force field and it'll still work.

I think you need to take a fundamental physics class.

Or lessons on how to troll better.

I don't even think there is a force field that would act on the ball spring system in the way you described. I've never heard of an ideal spring being stretched some length, let go of, and NOT returning to equilibrium.

my problem is that it is ACCELLERTING thus there either is a force acting upon the spring outside the system, which should cause it to behave in a different manner, or there is no force.

okay let's take two scenarios and see if you can tell me the difference between the two.
let's say I'm accelerating upward in a spaceship at the rate of g. i hold a spring. the spring stretches toward the force as expected. i let go. it oscillates during free fall, as expected, and falls to the ground.

now let's say instead I'm coasting at a constant velocity in a spaceship, but there is a powerful magnet pulling both me and the spring downward. i let go. this time the spring won't oscillate during free fall but stays stretched out.

would you agree? now which one models gravity?

violence you certian of thatcause i would dearly love to see that experiment.

No, it should not cause what you think. Lets imagine a more simple system.

Take two balls, with a slack string between them. If you pull one ball, the string will eventually get taut and will pull the other ball too, but this takes a little while to occur.

If you pull both balls at once, at the same rate (i.e. same force on each), the string remains slack and both balls remain stationary in the rest frame of either.

This is basically the same system - there is a force on the system, but if you just look at the string between them, you can't tell because it remains slack.

The difference here is similar to the gravity system. In one case, there is a force on one ball, which makes the string taut because only one ball moves. Thus you observe the effect of the force on the system, even if you are in the rest frame of any part of it. In the other case, there is an equal force on both balls. Although there is a force on the system, the system does not change (in its own rest frame), but it is still subject to a force.

The system thus does not 'behave in a different manner' because of the force. The balls remain the same distance apart, the spring remains slack. This does not mean there is no force.



The spring would actually stretch away from the force, if you're holding it in your hand, because it's being pulled from one end. This is not like gravity, because the force causes the system to change internally (it only acts on one part), as opposed to acting on the entire system at once and thus not being noticeable in the system's rest frame.



This scenario is not clear to me. Is the magnet exerting an equal force upon every atom (note: a magnet will not actually do this, but we may make up a system where it does. We must nevertheless understand that this system is not physically meaningful in the context of magnets)?

If you drop the spring (which is already stretched) and the magnet pulls the entire spring equally, this is exactly equivalent to gravity, and the spring does oscillate, as described earlier.



Assuming I understand what you mean in the magnet scenario, this one models gravity, but the spring does oscillate unless it's at equilibrium when you drop it.

Philip, all you have to do to prove me wrong is to show me one situation where you pull a spring taut, then let it go and not have it return to equilibrium. It basically comes down to you proving that a spring is not a spring in the presence of some kind of uniform external force field.

By all means.

Violence is entirely correct, assuming the magnet acts on every atom simultaneously (which isn't really physical but, again, we can postulate in a thought experiment).

It doesn't matter what causes the force, though it seems you think it does. This is a fundamental misunderstanding. The mechanics of the situation are independent of the cause of the force, they only depend on the magnitude and what the force acts upon.

In the case of gravity, the force acts on everything in the same way, which can make is unobservable in the rest frame of the system (looking at the system only, not anything else as a point of reference).

In the case of pulling one end of the spring, the mecahnics are fundamentally different. Although you may exert the same magnitude of force as gravity, you aren't exerting it on everything simultaneously, so the behaviour of the system is different.

but all magnets do indeed decrease force with distance squared (as does gravity i'd like to point out.) gah! just no winning with you guys.

Whilst this is true, in these systems we are making the standard approximation that the force is the same everywhere. If you calculate the difference in gravitational force on the surface of the Earth, and a few metres higher, the difference is negligible for the system dynamics.

Unless you dispute this, the 1/r^2 nature of the force is not relevant to the discussion.

If you do dispute this, you have hundreds of years of measurements to explain away.

Yes, they do, which is why this is a thought experiment with a relatively uniform field. Even small differences wouldn't cause a spring to not oscillate in midair.

There's no winning here because as far as I can tell, you need to take an introductory Physics course.

i guess i don't understand why my first scenario with the space ship wouldn't be functionally equivalent to gravity. sorry, you did explain it to some extent anmal, and far better than my own explanations have been. but can you delve further?
sorry I'm trying to wrap my head around this. i agree the motion would be opposite to the force sorry i should have stated that better.

I'm not sure how to say it better than I already have. Gravity acts on every particle simultaneously, which means they all accelerate in the same way because of it and, in their rest frame, the force can be completely ignored.

In the spaceship, if you're holding the spring, this is exactly equivalent to pulling on one end of it (because the spaceship pushes you via your feet, and you pull the spring). The end you are holding accelerates, which pulls the bit below it, which pulls the bit below it, etc. The force is different on the different particles. The overall effect is to pull on the spring, and extend it. This is different to gravity for the same reason that pulling on one sphere (in my previous post) is different to pulling on both spheres. Do you understand that scenario, and how the two spheres behave differently depending on whether you pull on one or both?

but in a uniform magnetic field would it not be the case that every particle is pulled uniformly? and if so, why would the spring stretch out, or i be held to the ground?
hmmmm. i think i see the problem now.

Well...assuming every particle is magnetic in the same way and has the same orientation, yes, every particle is pulled uniformly. The spring would thus not stretch out, and I don't believe anyone said it would, though perhaps there has been a mistake or typo.

However, if you held the spring up so that it was stretched (pulled in the direction of the force), then let go, it would oscillate as it moved - just as in the gravity situation.

alright that makes sense anmal. THANK YOU!