Ragebait answers only
Everyone else is wrong. (Ragebait.)
Speed of approach = speed of separation.
If the box left the blue portal at a slower speed than it entered the yellow one, the top of the box would be moving slower than the bottom of the box, which would compact the box dramatically during the transition, but we can see that its size is unchanged and it is still square.
The top of the box is pushed rapidly out of the blue portal by the bottom of the box being thrust into the yellow portal. (The bottom of the box is pulled rapidly up into the air by the top of the box which is already moving quickly.)
The object going into the portal has no momentum so it would be A.
No momentum in relation to what? Momentum doesn’t exist in isolation.
Momentum relatively to the source game engine grid.
“speedy thing go in, speedy thing come out.”
So A.
As I said, there is no “speed” in isolation. Speed is a relative property of an object and a reference frame (i.e. another object, like e.g. a planet)
In this particular case it is speed with respect to the fixed reference frame of the game.
To the space outside of the blue portal. Moving the orange portal doesn’t drag the whole surroundings, so assuming both places are on the same planet, the momentum of the box in relations to both places is the same
Moving the orange portal kinda does ‘drag the whole surroundings’. It moves an entire universe.
The cube is stationary relative to the universe of the platform it’s on, but it has momentum relative to the universe through the portal. The question is which universe is the cube in? What is the boundary of the portal surface?
As Optozorax taught us, gravity must act through the portal.
Well, it doesn’t in the only source of knowledge we have: the game Portal. I don’t know enough about gravitational forces to have a coherent theory on it, gravitational waves moving through space-time is a bit beyound my real understanding. But in the game if you put a portal on a ceiling, it doesn’t “suck” you until you’re throuth it, so there it isolates gravity somehow.
At this point, I consider Optozorax’ research the primary source of how portals work. If the games disagree, they’re wrong.
If you stick to the premise that the portals exist in a universe with GR, then we can pay much know that space-time is locally flat in and around at least the middle parts of the portal. We know this because things don’t get fucked up when they’re going through.
Stop stealing all my upvotes
You asked a question and they gave an answer. Why wouldn’t they get the upvotes?
I’ve just never had a comment on my post get more upvotes than the post itself.
Am angy
and upset I didn’t think of posting that image in the first place
Perfectly understood the assignment, 10/10, no notes.
There’d be no cube but yes
In the first moment of exit, it might look like this though
deleted by creator
Portals aren’t real and so work however you want them to, but people rarely consistently apply their models.
I’d say A given how they work in the games though. Only the object’s momentum is conserved. The portal doesn’t transfer momentum. There may be a slight breeze coming out of the blue end as the column of air in front of the portal-plate is pushed in, but the cube is just going to flop out.
Speedy thing did not go in
It should be a.
Imagine if the cube was actually a long rod and the orange portal start with the column half way inside it. Then the orange portal moves, in this case it would be very odd for the rod to jump in this scenario like in case b, the thing you would expect would be for the rod to stay still (besides tipping sideways a bit) consistent with case a.
neither, no portal rules were given. Please create an Aperture support ticket.
“Speedy thing goes in, speedy thing comes out” as the cube isn’t a speedy thing (no speed lines) going in, it won’t be a speedy thing coming out.
Niether. Moving surfaces break portals instantaneously.
Portal 2 has moving surfaces, with the cop-out that it’s accelerating surfaces that cause the portal to break.
spoiler
No matter that you literally put a portal on a different planet…
Portal 2 (story mode) only has laterally moving surfaces, that inherently don’t cause things to enter the portal. The moon portal is stationary in the engine.
Ragebait answers only
I’m giving so many people Fs on this assignment because you failed to read all the instructions.
The correct answer is B due to the graphical conservation of speed lines.
I did it deliberately.
Lemmy reads more than most but people aren’t good at reading
I think any answer is a ragebait answer because nobody here understands physics
That’s definitely a ragebait answer
Judging by the most highly voted answers on physics.stackexchange, it’s also true.
Trick question. Fun answers are not ragebait. Serious answers (correct or incorrect) are ragebait. You get an F.
You can’t place a portal on a moving surface in either game, so neither.
you can in one specific spot in portal 2!
Two, if you count… the big one at the end
it doesn’t look like it’s moving though. and considering how many things in portal 2 move when they look stationary or vice versa…
As far as the game engine is concerned, “stationary” is relative to the… other comparatively big thing: the former big thing is moving very quickly around the latter, even if it looks stationary because it has a lower angular velocity
pretty obvious tbh
So now we just need to build this test in there and we are set
So the cube is just smashed?
It’s a practical answer which is slightly upsetting because I wanted more discourse.
No, cubes cannot be destroyed by crushing. The portal disappears when the surface starts moving and then the cube stops the surface’s descent.
what about the portal on the moon?
Well, everything is moving or not moving, relatively
Someone should write a thesis on it (or whatever it’s called). Could call it something like The Relativity Theory.
It’s unstable and will dissipate on its own when the relative displacement between them will be too great.
Skill issue
You’d make a horrible scientist.
It said ragebait answers only ¯\_(ツ)_/¯
If it is a question of real life physics, then B would be correct
Damnit, you are correct, my bad.
Scientists know when to use existing knowledge.
This was answered decades ago
In that situation both portals (the inside and the outside window frame) have equal, but opposite velocities and therefore cancel out any momentum from the person.
When dealing with OP’s scenario, only one portal is moving.
wikipedia.org/wiki/Steamboat_Bill,_Jr.
Nearly a century ago. Fun fact, this movie inspired Steamboat Willie, the very first appearance of Micky Mouse.
The problem with this analogy is that both sides of the window are at the same point in space so there is no pressure differential. What if the blue portal was at the bottom of the Mariana’s Trench? What force displaces the water to place the cube on the other side?
It wouldn’t. Same as if the other side of the portal was a brick wall. It wouldn’t go through or would be smooshed by whatever force is driving the portal.
I guess the odd thing is, if the orange portal can be moved, the pressure from the brick wall would be directed at the attachment point of the orange portal, otherwise why wouldn’t the orange portal keep moving, since it is not “touching” anything?
If the blue portal was deep under water, the pressure would force the water out the orange portal.
Neither. The cube is not making contact with the portal at all, since the portal is on a stationary block with some speedy lines drawn on it. Speedy lines don’t nake thingy go fast - everyone witb a gel-hairstyle knows that.
EVERY GIT KNOWS FAST LINES AIN’T DA TRICK! RED IZ WOT MAKES THINGS GO FAST!!!
Next you’ll claim stink lines don’t make something stinky.
These heathens! Arguing against centuries of line faith! Draw heat wave lines around them and make them burn up!
B.
Momentum/velocity is not an intrinsic property of an object, it is a relative property between two objects in a frame of reference.
Behind the yellow portal is the part of the universe where the blue portal is. The yellow portal, and therefore the space where the blue portal is, has momentum relative to the cube.
Put yourself in the frame of reference of the cube. You see the yellow portal come toward you. Imagine there are objects on the other side of that portal. You see those objects rush toward you through the portal. Why would the objects just stop dead when you came through the portal? (If they did just stop, it would be as though you hit a wall, and you wouldn’t actually go through the portal at all.)
Agreed. Also consider the duration of the time that the portal is passing over the cube. It is moving at speed, the entire way through the portal and out the other side and then it just stops dead immediately once through? That would hardly be a conservation of momentum anyway from any frame of reference and does not make any intuitive sense.
This exactly. Consider an object that isn’t a point mass (like the cube) going through. As the first atoms go through: if they just stopped relative to the portal boundary, that would suggest the next layer of atoms need to exert force on the first layer to push through. But portals in the game Portal do not have any resistance to objects passing through them.
Portals don’t stay on moving platforms.
But if they did, it would be A as the cube itself has no momentum.
WHAT DID YOU NOT UNDERSTAND ABOUT RAGEBAIT. ANSWERS. ONLY.
… Uh
u mad?
So really I saved this comment and you’re all welcome.
It seemed to work.
Except that one time when you use portals to cut the neurotoxin pipes.
Yeah, but those are moving from side to side. To my recollection, you never see a portal in a wall that’s moving in a direction that’s perpendicular to the plane it’s in.
The speed of one thing is the same speed of the other if you change the reference point. So the cube has momentum but the moving platform does not. It’s more about having a velocity in respect to the portal it’s going in or coming out of or an average of both. Like when you jump into a portal, you come out faster on the other side. Now what if that out portal was traveling at the same rate? Would you be traveling just outside the portal or double speed (in relation to the ground and static objects in the same room)?
