Ragebait answers only
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.
“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.
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.
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.
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.
Speedy thing did not go in
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.
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)?
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.
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.
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!
https://www.youtube.com/watch?v=B19nlhbA7-E
Not providing a link to alternative platforms is my ragebait
In addition https://www.youtube.com/watch?v=DydIhwLrbMk which tries to make portals act “real” by treating them as spacetime with an unusual (but not mathematically disallowed) geometry.
Yes, they are fictional, so they behave however Valve (and fan works) want them to behave, but trying to bridge the gap between fictions and current physics models and be a fun and enlightening experience.
It would probably be A because of Newton’s first law of motion.
because of that law it is B ;). the cube “teleports” into the reference frame of after the portal and in this frame it is highly in motion.
it’s like you trying to jump on to a moving train, you first need to match the trains velocity (speaking relative to earth), then you are at rest in the trains frame.
this kind of thoughts is what makes special relativity so cumbersome.
The real answer is the enemies we made along the way
Was going to post the correct Answers (A) but then looked at the post and though na. But if you want to know more about portals and how they would work in real life check this out. Great guy.
and his answer: https://optozorax.github.io/portal/?scene=speed_model
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.)
