Thoughts? Trying to oversee a debate between two friends on this. Wanna see what ye think

Thoughts? Trying to oversee a debate between two friends on this. Wanna see what ye think.

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A.

None.
Portals close on a surface that moves.

a

A. The cube would keep it's original momentum

This, ignoring of course that the portal would close when the platform moved

Why? Why no transfer of energy?

Because the piston has momentum, but isn't going anywhere.
The cube has no momentum, therefore it just falls down.

This. Portals must maintain a constant distance reference. The picture op posted is literally nonsensical. Its equivalent is like saying " down garble berry chib itd a malorky"

Imagine two friends lifted up a door frame and held it over you. They then drop the door frame so that it falls around you. Do you go flying into the air or are you still just stanfing there?

but there's moving portals in the game

Portals break conservation of momentum, which is a fundamental law governed by the way you measure distance, but also a logical constraint.

If conservation of momentum is broken, you get a paradox, namely both of those options are correct.

Both are impossible. The cube itself has no energy, so it cannot move.

B is impossible because it forces the cube to gain energy from nowhere.

A is impossible for a more complicated reason. As the moving portal overtakes the cube it does not magically cause the cube to maintain its structure on the other side. Instead, because the cube is stationary, each layer of atoms would begin piling on top of each other in a perfectly flat line. This would likely eventually lead to a fusion explosion killing all of the retarded scientists nearby.

let a = b
Then a2 = ab
a2 – b2 = ab – b2
(a-b)(a+b) = b(a-b)
a+b = b (divide by a-b )
b+b = b (as a = b)
2b = b
2 = 1

Ooops, someone divided by zero.

As far as I can remember, objects accelerate only if a force is being applied to them (Newtons' 2-nd law).
I don' t see any force being applied here to the object, so I would say its A.

It is also possible that due to the nature of the portal some force is being applied to the objects that go throught it. In this case the object would accelerate, but since portals are not real the question is moot.

This, I've heard it described as compressing space infinitely.

>a = b
>a - b = 0
>divide by a - b
>jenius

Isn't there a part in the second game where you put a portal on a moving platform to cut some pipes

my take using simple conservation of mechanical energy. so B

Yeah you're right

According to GLaDOS herself. speedy thing goes in. speedy thing goes out. the cube is stationary and due to momentum being preserved by the obvious laws of the cube it would fall out. not launch out. its like if you slammed 2 doorways together. anything in between would just stay whatever speed it was at

thank me later
>iFuck Tonight.com

depends on the frame of reference.
Having the wall move or the cube move is the same, you're throwing energy in a system either way.

Just as the massive autist that isstated, B's probably right.

Move relative to what?

To anyone who says A: Imagine the momentum of the top half of the box when it's half way through the portal.

hey its not just autism if its put to use

relative to the door frame you fly out of it. the momentum must be conserved, there for its B

Why doesnt someone just try this i am pretty sure tbere is already a mod where they have a portal hydraulic press someone would just need to change the map a bit

It depends on the time.
If it's closer to dusk then the portal is just moving around the sun at a slower rate than the cube so scenario A would be observed. If it's closer to dawn then vice versa and scenario B would be observed.
Then the answer would depend on what time the person who made the mod decides it is.

*faster rate than the cube

Um portals aren't real

still autism. Good handwriting and sketching tho. Mechanical engineering student?

Neither A or B,

It's actually B but then gravity added... so you get a curve.

aerospace eng

Imaging particle X, this is a particle on the upper most side of the cube, the side closest to the portal. As the portal moves down towards the cube with a directionless velocity of V relative to the observer. What velocity will the particle X have as it exits the portal?

Of course particle X will have a velocity of V, this is the same for both scenario A and B, i think that we all can agree on this. However in scenario A, particle X will loose this velocity V when the entirety of the cube have been transported through the portal. Now i ask, how does particle X lose its energy in scenario A?

It is not possible, therefore the answer is scenario B.

The momentum IS conserved, the item the moving portal is attached to will collide with the stand and produce heat/elastic potential energy -> kinetic energy as it moves back up. If the piston moving down slows and never touches, then the energy is dissipated as heat in the friction causing it to stop. Regardless, B is not possible. A conserves momentum. The portal in and of itself does not transfer energy to the cube, it just teleports the atoms to a different area in the same orientation and in the same energy state they were at before.

A. The cube has no velocity.

This is not an answerable question, because not enough is known.

What if this takes place in a near zero gravity enviornment and the cube weights 1oz? One might be more inclined to think B if the surface of the portal can impose even a small amount of energy to the cube.

If the cube is heavy, and under earths gravity, one might think A is possible, but if the portal cannot impose any forces on the cube itself, then sliding down the incline would be more likely, but even that would depend on friction between incline and cube.

A lot of different things can happen, especially because there's just enough ambiguity in exactly how the portal works to create this type of conversation.

yes but you would agree that the cube has to exit the portal with a velocity right?

if so see if not then plz explain how the cube exits the portal.

The portal only changes the position of an object, not momentum. The object is at rest, and at no point does it make contact with an object that can impose a change in momentum. Unless the portal is The Same object as the item it's mounted on, and can somehow magically give energy to at thing going through it (how the hell would that work?), the item will simply have it's atomic structure moved to a different place in the same orientation and energy state it was before.

Are you at total rest right now? No cuz you are drifting through space at incredible speeds. Velocity and momentum always depend on a point of reference. Asuming the piston moves at constant speed, the piston is a good point of reference to apply conservation of momentum, and to realise the answer is B

"The portal only changes the position of an object" But that's wrong, that would be teleportation.

A portal is a doorway, the nature of portals is that you walk through it. Therefore you need a velocity as you exit it. If you have no velocity out from the portal how can you exit it?

To phrase it in a different way. If the orange portal only covers 5% of the cube, where will the cube appear on the otter side? It will appear close to the blue portal right? or will it appear at one cube length (- 5 %) from the blue portal.

Se figure, in scenario 1 the cube moves through the portal, thus the cube must have a velocity. While in scenario 2 the cube renders at its final end position. I think that we all can agree that the only solution is scenario 1.

I don't think you understand how point of reference works. At all. It also has nothing to do with imposing momentum on an object, since that doesn't change with point of reference. It depends on energy available to the system and efficiency/ability to impose it on other objects that interact physically/with fields.

Look kitten

At this shit (Literally, it means 'What sort of dick')

Russian is weird

Yes but in this case it is the portal that has the momentum, the cube doesn't have to have it if the portal does. I also said scenario 1 is the correct option

This one is a thread closer. I tried to prove it to you using conservation of energy. Since some of you still dont believe, continuity is another simpler way of proving that A is absurd, therefore it has to be B

Ok, would you say that the cube exits the portal with the same velocity as it enters?

It would make sense for it to since we have no reason to believe the portal gives the cube energy

well that makes no sense because anywhere you put it on Earth it'll be moving.

Only A

Portal on moving surface. A is the answer
youtube.com/watch?v=mCQiwhik8nc

So if the cube has a velocity as it exits the portal, why does this velocity disappear. As it would have to if scenario A is correct?

Or rather as the cube is in the process of exiting the portal the cube must have a velocity, then it stands to reacon that the cube has a certain kinetic energy. What happened to this energy as the cube have completely passed through the portal?

Can you make that a little clearer it's hard to tell what you're trying to show

No, I'm saying it WOULD NOT have velocity. Just because velocity is required for it to pass through doesn't mean that the portal transfers it's velocity to the cube. Thay would mean that the portal and/or object it's mounted on woup lose momentum. Since there's not feasible way for that to happen then the portal will continue to move at the same velocity while the cube exits with 0.

He's saying it somehow exits the portal at a speed of 0.
He's a fucking moron.

you sound like the moron. What exactly would give it speed? What magical process gives the cube momentum without taking energy from somewhere else and without contact with a field/physical object?

>exits with 0
>moves without moving
Fuck off, retard.

At time t1 the box is "inbetween" the entrance and the exit. One instant delta t later, if the entering part of the box was moving and the exiting part of the box had no speed, there would be a missing chunk of the box which is nowhere. Due to the principle of conservation of mass, this is imposible. Therefore the box needs to have the same speed when it exits the portal

>Thoughts? Trying to oversee a debate between two friends on this. Wanna see what ye think.

A, the block doesn't have any velocity

The portal can continue to move without making the cube move. Cube can teleport without gaining momentum. Fucking moron

Now i am a bit lost, as the cube is in the process of exiting the portal. Mind you the cube has not completely exited, it is in the process e.g. half way throu.

Let's say that i am sitting on the blue portal side with a radar gun (equipment used to measure velocity of moving cars) and measuring the velocity at the cube as it moves through the portal. What is the velocity?

Given that you have already agreed to scenario 1 in

So basically you argue it's impossible to properly reconstruct an object when the exit portal is non moving because the next layers would have to push the previous ones forward. That makes sense. But if that's the case then where does this energy come from?

It is A. because the portals function on basic premises that the velocity of an object that enters into a portal is maintained, and the effects of the orientation of the portal entered into will be abided by.

Since the object has no initial velocity when it travels through the portal, but has to reorient to the forces of gravity applied by passing through the portal, it will harmlessly fall out. The only other effect would be it bouncing a bit as it tries to rectify the orientation between the two portals, but the assumption here is that the platform is blocking the object from completely travelling into the portal and thus acts the same as if a cube was sliding down an incline. A. is the correct answer.

I see the issue. I think it's a fundamental problem with portals. The object has to be moving for it to reconstruct itself from the exit portal, but it also has to gain this momentum for somewhere. Of the object isn't moving, it's not possible to reconstruct it. And the portal as far as I am aware has no explainable way to transfer energy to the object.

The energy that seems to appear from nowhere is the kinetic energy that the box has when you measure its speed from the piston point of view. In other words, its the kinetic energy the box has because of its relative velocity.
Saying that the piston is aproaching the box at a speed is the same as saying that the box is approaching the piston at that same speed.

It doesn't matter what gives it speed, it can't exit the portal with 0 momentum. You're saying that the cube can continuously change position over time without speed.

Imagine the very top atom of the cube the instant it goes through the cube, according to you it has no velocity and so will remain in the same position until acted upon by a force. Imagine the same atom an instant later. Where is it? Where is the atom just below the top of the cube?

Velocity relative to what?

Where does the energy come from, that is indeed a good question.

The only thing that i can think of is that there must be some sort of resistance between the object and the orange portal. So in effect if the orange portal moves with a a total kinetic energy of X, and the cube exits the blue portal with a total energy of Y. The resulting energy that the moving portal has after the cube have been transported would be X-Y.

regardless of the hyopthetical nature of a portal, theres no reason why the cube should go flying. it would simply slide down the wedged block, as it has now reemerged on an angle.

>in the game
Yes. In the game.

A, obviously. The speed at which the portal approaches affects only how fast the object will appear on the other side. It won't add any kinetic energy to the object.

>down garble berry chib itd a malorky
you better watch your tongue nigger

Portals are magic doorways in space. "Where" it gets the momentum doesn't matter at all, all that matters is that in order to exit it has to have momentum.

Sure ok but clear this up for me because it's confusing.
They move toward eachother say at 50mph. Orange portal throws box out of blue portal. Box is not moving 50mph woth reference to blue portal, but the orange portal is still moving 50mph. Now if the blue portal launches it straight up, say at the same orange portal, they will move at eachother at 100mph

>implying you can have any knowledge about the concept of real portals outside the game

You're not imparting anything to the cube though. The moving platform doesn't touch the cube at all because there's a portal in place of a solid surface. Your autism is weak.

Only on Sup Forums will the fucking physicists of the future come together to debate a fucking portal and a box. Good fucking job.

It does depend on the nature of the portal

Take the Stargate, Objects leave the gate at the speed they entered relative the the event horizon, So the cube 'should' do B. -In fact a 'moving gate' scenario was to my knowledge a feature in both :SG1 and Atlantis.

But take the game Portal, since the cube has no momentum it should do A.

This copy pasta thread exists because these terms aren't defined, This version doesn't even label what the "holes' are, and so we cannot reach a conclusion.

That is a good question. My guess is that as soon as you star moving one of the portals, the whole universe starts to move (therefore has momentum) for the other portal. Anything that passes through one portal which is moving, has to exit at the same speed due to conservation of energy in the whole universe.
But it would be interesting to consider that every time two portals are active at one instant, the whole energy of the universe doubles. That would explain a doubling of the relative speeds of the box

If you live within our realm of physics and not fantasy land, it's A.

Assuming the portal didn't close when moved probably B.

The blue portal is unmoving but the orange portal is slamming down. When it comes down to it the cube can be treated as the one moving once the orange engulfs it. There is no A. If the cube isn't moving and therefore can't move even why would it even be able to plop out? No motion is no motion. No motion means a traffic jam of crushing proportions or worse.

The equivalent experiment would be to have the cube pedestal move instead of the orange portal. Relative to the blue the cube is in motion. Looking through blue you'd see the cube, it's pedestal, and the room flying towards you as orange descends on it rapidly. Why wouldn't the cube fly out? Relative motion becoming actual motion because portals are fucky in the first place.

Portals are strange from the start. It's not exactly that hard to believe they'd behave oddly.

Nice dubs

A

A.
Think of the portal as a hula hoop. The object isn't moving, the portal is.