Cmon Veeky Forums solve it, and proove that youre not a brainlet

The first letter of a sentence gets capitalized. Most modern phones do that for you automatically. Are you really on your phone op?

Devil trips sage

C.

turned it off.

if yer in space
and you don't see shit except a rock which appears to be getting larger
and then the rock and your abdomen collide
did you hit the rock, or did the rock hit you?

Unless the cube is a discrete entity that can only exist on one side of the portal or the other then each horizontal segment of the cube must come out of the blue portal at the same relative speed that it enters the orange portal, lest segments be crushed by other segments.
This would impart it with the speed of the orange portal.

Alternately consider the weaker frame of reference argument.
If you throw a ball off a moving platform at the same speed that the platform moves in the opposite direction then the ball will be at a standstill from the view of an outside observer and will only drop vertically.
If you drop a door over an object then object will be at a standstill. This portal is not a classical dropping door. One part of the portal is in motion and the other is not.
In the example of the moving object and thrown ball this would mean removing the thrown speed or the speed of the moving platform and the ball would then move in the direction of the platform if it was dropped and in the opposite direction at the same speed if it was thrown (While still dropping vertically exactly like in the prior example) from the view of an outside observer.

The frame of reference argument gets kind of weird though and the physics of portals aren't exactly defined.

They are but the only thing that they interact with in that instance is lasers

...

Portal b sees portal a moving at x velocity
Portal b sees cube moving at -x velocity

Cube plops
>hula hoops
/thread

The cube IS a discrete entity that can only exist on one side or the other in game.

If you drop a cube in a portal that's side by side to the other one, you get the same side poking out both portals at the same time.

This is opposed to seeing 1 half the cube in and 1 half the cube out. The game just redraws the object as it enters/exits. It never actually "travels" through some extra space in between.

Velocity entering the portal is conserved, so B

explain how that's relevant if gravity is part of the question

B.
Cube has relative motion to the environment across the portal and nothing stops it. If you are on orange side, it doesn't matter what the cube does, but on the blue side it only makes sense that the cube carries its momentum.

kys

The entire picture is false.

First of all, portals don't get stuck on walls, much less move along with it. This representation was loosely based on the video game Portal, made by Valve, and failed to realize that since it is based on video game physics, it cannot be accurately answered based on real life physics.

For a video game physics answer, a video was made in accordance with the game engine itself.

nobody said gravity was part of the question
and even if it were, the force of gravity is weak as fuck so in this demonstration the box would overcome it anyway if we're going with the B model

A, in real life and in Portal itself.

it would be B, if it was possible

Portals vanish when placed on a moving surface to prevent shit like this from happening

B. We can very well look at the image as the cube moving towards the portal, instead of the other way around. This gives the cube velocity, causing it to shoot off.

A.
Glados herself says that Portals conserve momentum of the object entering the Portal. Not to mention that Portals can't transfer momentum because they don't physically collide with the cube. Thus, the answer is A.

"Speedy thing goes in, speedy thing comes out."

The further expand my answer, I'll quote GLaDOS herself:

"Spectacular. You appear to understand how a portal affects forward momentum, or to be more precise, how it does not."

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

The answer is A

It's B
The cube has to come out of the portal at the same speed it goes in.

from the reference frame of the orange portal, the box has a ton of momentum

This is literally
>what if magic was real
So any outcome you can make up is equally valid.

Can see that \sci\ is still full of brainlets.
Answer: it can be either A or B depending on the relative momenta of objects

Consider the following equation
[math] | \vec{p}_{box1} + \vec{p}_{orange} | = p_{box2} [/math]
note that it's impossible to determine the direction of resulting momentum from only the LHS.
For that you need to know the normal vector of the blue portal.

Anyway to produce A you can do the following
>have the mass of the box [math] m_{box} >> m_{orange} [/math] than mass of surface carrying orange portal so that the added momentum is insignificant hence [math] v_{box2}

porange is 0 though, portals don't weigh anything.

I've assumed the portal inherits mass and velocity of the object it's attached to.
If the portal is massless then the only result is A.

The portal itself is a position in space, and therefore has no mass. In fact if anything you just proved that the momentum of the cube will be conserved.

Also the orange "entrance" and the blue "exit" are just illusions, in reality there the same point in space.

I don't think it makes sense for the portal to inherit the mass, or rather even if it does it doesn't make sense.

The portal is nothing but a hula hoop, doesn't matter how fast I bring down the hula hoop, or at least that's the way I look at it.

The plop is too much also, it would just slide down the side.

If the bottom thing was coming up instead of the top thing coming down it'd be B.

> In fact if anything you just proved that the momentum of the cube will be conserved.
Portals don't conserve momentum only magnitude of momentum. I stated this without proof since this is what happens in the games from what I know. The reason direction is lost is because you can't know the output cube's direction from just the direction of the input cube and orange portal.

ie for a fixed orange portal and cube entry the output cube direction can be arbitrarily changed by reorienting the blue portal.

>thought experiments are meaningless and I refuse to engage intellectually with things I don't understand

If you're not an engineer already, you should consider switching majors. Sucking dicks seems more your style.

correct. I only just realised that there is no momentum transfer between the orange portal and the cube.

It seemed weird how you can go to the inertial frame of the orange portal and still have the cube plop out of the blue portal until I thought about this some more.

The cube does appear to be moving towards the portal relative to the orange portal, BUT SO IS THE BLUE PORTAL and at the exact same speed as speed as the cube.

So another way of looking at the problem is the orange portal is staying still and the cube and blue portal are moving up. So after the cube goes through the orange portal it comes out of the blue portal still going at the same speed, but the blue portal is also moving at the same speed. Looking again in the stationary frame of the blue portal you see a stationary cube come out.

So yeah the only possible solution is A, which is true in all reference frames.

Gotcha, makes sense.

Inertial frame arguments only work if you remember the blue portal will also be moving in the stationary frame of the orange portal

see

I think this is definitive, there is no other answer that could be correct I think.

as said, portals don't make sense according to our current understanding of physics

I'm pretty sure you could use a ceiling/floor portal loop as a perpetual motion device, as well. Nobody knows if/how wormholes work, so even if a portal such as this could exist we couldn't answer this question in a valid way without knowledge that isn't available yet.

>BUT SO IS THE BLUE PORTAL
but the orange portal doesn't know this
all it knows is
>object passed through me at x velocity and y angle
so all it can send to the blue portal is
>this object is exiting you at such and such a velocity and angle

>I'm pretty sure you could use a ceiling/floor portal loop as a perpetual motion device,
I don't view this as a problem
just like any other device, it's going to cost you at least as much energy to teleport the object to the ceiling as you'd gain from it falling to the floor

Portals dont teleport though thats the point

ok, replace teleport with the word 'transport' in my previous post

to quote portal,

speedy thing goes in,

speedy thing comes out.

the "thing" was not speedy, period

>but the orange portal doesn't know this
You're right. The cube comes out at x velocity out of the blue portal because the orange portal can't tell the difference between whether it's moving at -x or the cube is moving at x.
You've missed the point that the blue portal is also going at x velocity in the frame aswell.
So when you go back to the frame where the blue portal is stationary (ie x = 0) implies that the box is stationary aswell (x = 0).

It feels counter-intuitive and wrong for physics to work this way. And thats because portals are unphysical.

speedy thing goes in orange
speedy thing comes out of blue
but blue portal is moving at same speed as speedy out thing
so in the blue stationary frame a stationary thing came out
period.

>You've missed the point that the blue portal is also going at x velocity in the frame aswell.
but that's not necessarily true
what if the orange portal is on earth and the blue portal is on mars?

if the orange portal falls down onto the block at 100 meters per second, that means almost nothing because the difference in speed between the earth and mars is like 8 km/s

so, using your method, the block is going to come shooting out of the blue portal at like 23 times the speed of a bullet due to the difference in velocity between the earth and mars

instead, the orange portal should transmit to the blue portal that the object should be exiting at 100 meters per second relative to its own frame of reference

>What are frames of reference lmao

>if the orange portal falls down onto the block at 100 meters per second, that means almost nothing because the difference in speed between the earth and mars is like 8 km/s

there is nothing wrong here. assume cube comes out mars at 8km/s + 100m/s. Go to reference frame of mars and the 8km/s disappears and you have a cube come out at 100m/s

>so, using your method, the block is going to come shooting out of the blue portal at like 23 times the speed of a bullet due to the difference in velocity between the earth and mars

Yes because relative to us the MARS ITSELF IS MOVING 23 times the speed of a bullet. It helps if you keep track which reference frame you're in.

>if the orange portal falls down onto the block at 100 meters per second
Whoops read that as block falls into orange portal at 100m/s.
In the case the portal falls onto the cube we have the same problem as OP and you come out stationary on mars because you only get the 8km/s contribution from mars which disappears when you go to mars' frame.

I've tried to come up with a counter point but I can't, so I suppose you've convinced me
good show

Already been solved.

physics.stackexchange.com/questions/230762/portal-2-physics-one-moving-portal

> implying a bullet that you're flying towards won't hurt you just as much as a bullet flying towards you

oh look, its this copypasta again. This has already been solved back in fucking May, its A you fucking retard, momentum is conserved for objects moving between portals, the portals themselves do not generate momentum, nor do they transfer any to an object, the game itself directly states this multiple times.

Sage

>this neet is talking about video games
we were having a nice science discussion, you can fuck off back to /v/

kys OP

>a problem based on video game mechanics elicits a nice science discussion

don't give me any of that "but muh hypothetical" bullshit either

It's a useful thought exercise for Galilean relativity, which if you looked at the responses in the thread not everyone is good at.

If you want to shut down these threads for good create a counter copypasta that solves this problem and meme it throughout Veeky Forums so that these threads can be shut down in 1-3 posts by the hivemind using the counter pasta.

the portal does not do work on the cube ergo it cannot displace it. neither A nor B are valid. the only true thing that would occur is the destruction and recreation of the object, which means either A or B could be valid depending on the mechanisms contribution to linear momentum when an object has been formed, or whether it is simply reassembled. that is the only true scenario and anything more is just meaningless to discuss within the confines of science as it prevents the scenarios from even occurring.

guns confirmed for sucking people into their cone of fire

If gravity is not part of the question, then option A extraneous. kys

>extraneous
no, it's just an error on the part of the images author
instead of being on the ground with a "plop" noise, it should simply be hovering in front of the blue portal instead

You're giving no reason to believe that gravity isn't present. You're simply coming up with facts to fit the theory.

not really correct as the gun doesn't move relative to the target
it's more like

why do blacks keep flying towards stationary bullets at 400 m/s that were fired by white officers, do they want to get a whole in their head?
Bullets confirmed for dindu nuffin it was the blacks who ran into them.

whether or not gravity is present doesn't change the options
in model A the box exits the portal and appears to do mostly nothing
in model B the box exits the portal and appears to move with speed relative to the orange portals speed

This is correct.
The argument made in holds in the presence or absence of gravity.

You can nearly replicate this test at home with a slip of cardboard and a flyswatter.

A portal is simply a hole with a foreign exit point. Place a block on the cardboard slip. Cut a hole in the flyswatter and slam it down around the block. Does the block eject from its starting position? If the block did not eject from it's starting position, then you can consider A to be the right answer. If you live in a universe built around the Havok Engine, you may find that B is the answer.

then why isn't the cube hovering to begin with?

you're asking why a thing is drawn where it is in an image?
because that's where the guy drew it
it doesn't make any difference if it's hovering a foot off the pedestal or not

What makes you think that it isn't?
It can be hovering just above the platform and barely touching it.

motion
is
relative
(It's moving relative to the orange portal)

However, it is static relative to the blue Portal, which is what matters.

From the frame of reference of earth, the bullet moves and the nig nog stays still. From the frame of reference of a point in space, the bullet is moving at a faster speed than everything else, which is also moving. From the frame of reference of the bullet, the nig nog is flying into it and the gun away from it. Didn't you ever take a high school physics class?

> From the frame of reference of the bullet, the nig nog is flying into it and the gun away from it.
Based police officer trying to show nig nog that you need to fly away from bullets not into them but they just won't listen.

No it's not, it had to move at least one length of the cube to end up outside of the blue portal.

The starting cube is stationary relative to the blue portal.
>it would be weird if the post orange portal cube suddenly starts moving from the blue portal reference frame

The starting cube is moving in the orange portal reference frame.
>meaning the speed at wichs parts of the cube appear from the blue portal is proportional to the speed of the cube entering the orange portal. advocating option B.

I think its pretty safe to say that A and B cant both occur simultaniously.
though, they were both concluded from what info we are given.
This means we have a contradiction on our hands

I solve this contradiction by proposing that a blue and orange portal are unable to move with respect to each other.

you have no idea what you're talking about.
The cube doesn't "move" at all in the process.

1 m into the orange portal is 1 m out of the blue portal. The orange portal descends a cube length over the cube so the cube appears a cube length outside of the blue portal. Note that I said it appears and not moves. The cube never experiences motion in the stationary frame of the blue portal. The space the cube occupied simply goes to another place.

There is no contradiction, just use Galilean relativity carefully as did.

The cube changes its positiin relative to the blue portal depending on time. It'd be very silly not to call this motion.

A discontinuous change in position shouldn't be considered to be motion. This is closer to teleportation, but thats not really accurate because the cube doesn't instantaneously change position either. So I guess this process is best described as a gradual, discontinuous change in position. Not really motion.

Physics isn't very good at describing non-physical events.

What makes you think the movement of the cube wouldn't be continous?

For a cube that is displaced between two portals you can't draw a CONNECTED line in space that maps out the trajectory of the cube.
There will be a break in that line corresponding to the time when the cube goes through the portal.

e.g. at one time the cube can be at x = 4 and at the time after it goes through the portal the cube can be at x = 500, thats called a discontinuity in the position of the cube because the cube's position didn't exist in the range between x = (4,500) during the time it went through the portals

If you also allow stuff to go through portals instantaneously (no delay due to finiteness of the speed of light) then there is also a discontinuity in spacetime, but thats not relevant here.

Well, considering it's a VIDEO GAME. The solution is to use portals INSIDE THE VIDEO GAME and find out.

Science is about experimentation and observation. NOT mental masturbation.

You can draw a continous line between the two positions - through the portal. That's what it's there for - making two distant locations continous space.

The answer is A everyone else is a retard

Yes position is continuous in the frame of a cube (it's always constant) but it's also discontinuous in an external observer's frame, which is the point I was trying to make.

The only things that external observers and observers going through the portal can agree on is the magnitude of the momentum of an object going through the portal.

For something to be meaningfully discussed in a physical sense it must be able to be agreed on by all possible observers in all possible inertial frames. Position, and direction of momentum are not one of them for objects going through portals.

It's not appropriate to define something as motion for which an external observer sees as a discontinuous change in position.

It's been years. Why hasn't someone just nodded the game and tested it out (while making sure the basic laws of physics are kept in place)?

>For that you need to know the normal vector of the blue portal.
Is this trolling?

Portals can't stay on moving surfaces.

They did in two different games

The physics calculations are entirely different so you got results in both A and B

If I don't tell you which way the blue portal is oriented can you tell me which direction the cube will come out (up, down, left, right) when you throw it into the orange portal? You can't.

You need the normal vector of the blue portal to know which direction it will come out of.

>Does the block eject from its starting position?
Yeah, relative to the flyswatter it does. If you make the hole big enough to go around the block's platform too this is obvious. Why should the flyswatter stopping after the block is out matter?

The situation is impossible. moving two portals real active to each other would require moving nearly infinite amounts of mass, as you'd use physically moving the whole universe.

On the other hand, according to the game the portals use 'quantum tunneling' which dictates that option a would occur, should the portals actually move. The exit velocity of the cube is dependent of the cubes velocity relative to the exit portal, not the entrance portal.

It would actually go rolling downhill and spin off some distance horizontally. This is because acceleration due to gravity hits the cube as soon as it enters the second portal and gravity starts pulling it down as each part of the cube enters the hoop. Gravity is pulling it at an angle in reference to the first portal, so the cube actually gets some lift by the end of the trip through the portal, flies off the platform, but continues hugging the ground because gravity is the only force acting on it. Cube has no momentum itself that would drive it into the sky.

This is the true correct answer. Anybody who disagrees is a brainlet.

>The exit velocity of the cube is dependent of the cubes velocity relative to the exit portal, not the entrance portal.
The conclusion is correct but the explanation is nonsense, no wonder no one understands this. You don't need "quantum tunnelling" to explain this, in fact quantum tunnelling (small particles tunnelling through barriers of potential energy) makes no sense here. Just use high school relativity correctly and you should get the same result using sane non-psuedo-science methods.