Since the last topic of discussion burnt out quickly, I thought I could use this thread (if I may, Val) to ask a question...
So, who can help me figure the right answer, because I've been getting confused.



At first I thought it has to be A, since the cube has no momentum. But then again, we can use a moving frame of reference (where the stationary point is the portal) and then the cube does have the momentum, which in the other reference frame after exiting would mean it has to conserve that momentum. So now I think B.

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This post is intended for information only. Please do not reply to this message as responses cannot be read or acknowledged due to the stupidity of the user.

I thought of it such that the portal was just a square plate with a hole in it (not a portal), and the platform the cube was on to be stationary. I think that it would act just like A, because if you think of it the same way I did, the box doesn't move.

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One time when I was high, I thought I was in an ambulance dying. Turns out I was just eating sherbert.
-stufflikehearts-

If the platform with the cube were moving, then it would be B. Since it is not, it is A. The blue portal and the orange portal rely almost entirely on the motion of the object, not the motion of the portals themselves. The object has to be in a state of motion to be propelled through the portal.

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I suspect that in-game physics would assign a "momentum" value to the weighted storage cube in an absolute reference frame, which would be conserved in magnitude during portal travel. If that's the case, I think that A would result. However, if we go with "spirit of portal rules" physics (since I don't think that the game supports moving portals, and actual wormhole physics don't produce Portal-like effects) I would say B, since from the point of view of someone outside the blue portal, the weighted storage cube would be approaching, and its momentum would be conserved as it moves through the portal.

I think it'd be A. Just imagine the portals as a regular hole, except when you smash down the holed object around the box, you also tilt the pedestal on which the box is perched simultaneously. So imagine you're spinning both the pedestal and the stamper (I don't know the term or don't recall for such an object) from its straight angles into the angle at which the outward portal is angled at which point you smash them together. You'd then have the box tip over or stay in position angled depending on its friction. The objects would not make contact so I see no reason why it would transfer momentum, aside perhaps wind whooshing around it depending on its speed, like a big car going by you.

So basically a more detailed form of Icha's answer.

Momentum: A function of mass and velocity, is conserved between portals. In layman's terms: speedy thing goes in, speedy thing comes out.

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@Calek: The question is, if something that is stationary (zero kinetic energy) is engulfed by a fast-moving (high kinetic energy) portal that leads to a stationary portal, is the first portal's momentum applied to the stationary object?

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Or rather (since portals don't conserve energy regardless), which reference frame the portal-conserved momentum is based on, and whether in-game physics or pseudo-real physics is used.

The portal-conserved momentum is based on the object passing through the portal itself. These portals are just simple doors to other spaces, they don't push or pull.

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Putting a portal on a surface is equal to putting a hole in a wall.

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Soulchild: u thnk evry thng stupid.
DaCrum: Warbear, why did you suddenly become pretty cool? Stop it.

Hmm. I think that this may warrant a bitchin' visual aid.

The problem with A is, that the moment the cube is going through the yellow portal, it appears coming out of the blue one at a certain speed, and since blue portal doesn't start/stop moving, the velocity cannot be simply left, can it? The rate at which the cube will be popping out of the blue portal would be equal to the speed of the yellow one, I'm not sure the cube can then stop moving at that same speed relative to the stationary blue portal. In all fairness, if it was the cube being thrown into the yellow portal at that speed nobody would argue against B, and I think whether it's portal moving or the cube moving, due to interchangeable frames of reference both situations are equivalent.

So if the yellow portal is moving it becomes a moving frame of reference if we choose it in relation to the stationary cube. But then we have to make an assumption that all of the reality along with the blue portal is also the same frame of reference moving with the same velocity. So even if you think the cube has no momentum B would be the correct answer. The cube moving in case B is equivalent to the whole reality (the rest) moving in the opposite direction with the same speed, to compensate for the movement of the yellow portal.

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This post is intended for information only. Please do not reply to this message as responses cannot be read or acknowledged due to the stupidity of the user.

It's A.

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I'm terrible at physics but it's A mainly because I assume this:

No.

The momentum and velocity of the portal does not effect the cube in any way. The portal is like a hole in a wall that goes to a different location. The portal doesn't act upon the cube in any way, shape, or form.

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Soulchild: u thnk evry thng stupid.
DaCrum: Warbear, why did you suddenly become pretty cool? Stop it.

This is all irrelevant anyway, because you can't put portals on moving surfaces.

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Soulchild: u thnk evry thng stupid.
DaCrum: Warbear, why did you suddenly become pretty cool? Stop it.

Imagine, if you will, that the black line is a piece of paper with a hole in it. The hole is just big enough to allow the cube to pass through it.


The cube would pass through the hole in the paper, no matter how fast the piece of paper is going. The hole in the paper does not act upon the cube at all, because it is an empty space. Nothing touches the cube but the ground it rests on and nothing acts upon it, so it sits stationary as if nothing happened.

Now replace the hole with a portal and it's the exact same thing with a slight variation.

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Soulchild: u thnk evry thng stupid.
DaCrum: Warbear, why did you suddenly become pretty cool? Stop it.

There is one thing that makes this explanation seem a little off, and why the statement that portals can't work on moving surfaces is more relevant here.

Imagine the cube is going through the portal, take a high speed recording of it, you will see that the cube is going into the yellow portal with a certain number of cm per second being taken into it. This means it will be coming out on the blue side at the same rate. Keep in mind that at the blue portal it is only the cube that is moving, and it is moving out of the blue portal at the same speed at which the yellow portal is shoved on it.

Portal physics just isn't compatible with real physics.

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This post is intended for information only. Please do not reply to this message as responses cannot be read or acknowledged due to the stupidity of the user.

It is completely compatible with real physics, you're just over-thinking it.

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Soulchild: u thnk evry thng stupid.
DaCrum: Warbear, why did you suddenly become pretty cool? Stop it.

Maybe I am indeed.

Well I must put my mind to rest, so I'll go ahead and run the test myself.

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This post is intended for information only. Please do not reply to this message as responses cannot be read or acknowledged due to the stupidity of the user.

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Soulchild: u thnk evry thng stupid.
DaCrum: Warbear, why did you suddenly become pretty cool? Stop it.

no reason you can't put a portal on a stationary surface and then push a button to make the surface move

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I'm still the Queen of Dicks

You've played the games, right?

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Soulchild: u thnk evry thng stupid.
DaCrum: Warbear, why did you suddenly become pretty cool? Stop it.

yes, and I know there's never been an instance where you do that. but that doesn't mean it can't be done in a world where portal guns actually exist!

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I'm still the Queen of Dicks

There has, actually. Many times. Any time you place a portal on a surface that can move, as soon as it moves, the portal is destroyed.

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Soulchild: u thnk evry thng stupid.
DaCrum: Warbear, why did you suddenly become pretty cool? Stop it.