/sci/ - Science & Math

[Anonymous No.7368483]

Which one is it, /sci/?

[Anonymous No.7368490]

>>7368483
>Hey /Sci/, could you apply the laws of physics to my unphysical object.

[Anonymous No.7368495]

>>7368490
Apply the laws of physics, assuming that portals are possible and everything that's not related to them works exactly the same. It's a thought experiment.

[Anonymous No.7368502]

>>7368495
>assuming that portals are possible

But they aren't.

[Anonymous No.7368508]

>>7368502
What are you doing here if you can't think about something on a theoretical level?

[Anonymous No.7368521]

>>7368495
Portal physics are undefined with respect to moving surfaces. You would have to actually define the properties of portals.

[Anonymous No.7368528]

B, because relative to the portal the block has momentum. The work required for this has to be generated by either the piston or the thing that keeps the portal open (the physics is ambiguous here).

[Anonymous No.7368530]

>>7368483
Assuming the platform is moving at a constant velocity v, then from the reference frame of the portals this is indistinguishable from a moving cube approaching the orange portal with velocity v.

The cube will, in this reference frame, therefore exit the blue portal with velocity v.

In the stationary reference frame, this will appear as a stationary box entering the orange portal and exiting the blue portal at velocity 2v. Thus, I would expect B.

I am, however, making certain assumptions about portal behavior on moving surfaces; although this model seems intuitive to me, other equally-valid assumptions will produce A. So to answer this question:
>>7368521

[Anonymous No.7368537]

>>7368483
>>>/b/, because the block is still moving towards the portal.

This is way less ambiguous than the other portal-physics troll question that is commonly posted because the portals are still stationary relative to each other.

When the portals are moving relative to each other, *that* is when you get serious problems.

[Anonymous No.7368539]

>>7368508
thinking about something on a theoretical level doesn't mean making up bullshit. Without a gross amount of hand-waving one of the many things portals violate is conservation of energy, if you fall into a portal and then emerge from the portal at a higher distance, then you will have gained potential energy from nowhere.

[Anonymous No.7368540]

>>7368495
>everything that's not related to them works exactly the same

but this is impossible. For one thing one of the rules of portals is that they ca't be put on moving objects, but the entire planet is moving relative to something so the game violates its own rules.

Secondly the scenario in the OP picture violates even the game's rules.

[Anonymous No.7368569]

>>7368530
But think about what happens when cube is half way through the portals. If taken from the point of view of the portals, both halves can be seen as moving towards the stationary portals. So I think they would reach an equilibrium state as halfway through, and just continue moving along with the portals.

However, this same idea could be applied to the air moving through the portals. As it passes through the the orange portal it will blow out the blue portal, slowing the whole system down. In a vacuum this would occur with radiation instead of air. Thus it is impossible for portals to move at all.

[Anonymous No.7368574]

>>7368540
The world (I hesitate to call it a planet) and the Moon are both stationary in Portal or else the portals wouldn't stick to them.

[Anonymous No.7368596]

>>7368495
>Apply the laws of physics, assuming that portals are possible
>apply the laws of physics, assuming things that massively contradict the laws of physics


from a false assumption you can deduct all kinds of bullshit

[Anonymous No.7368604]

>>7368540
>For one thing one of the rules of portals is that they ca't be put on moving objects, but the entire planet is moving relative to something so the game violates its own rules.

There is no such thing as absolute motion, so "moving relative to something" doesn't matter. The only coherent way to interpret that rule is that the portals cannot move relative to each other. And that rule is not being violated here.

[Anonymous No.7368609]

>>7368596
yeah like that a projectile moving through the air doesn't lose kinetic energy.

[Anonymous No.7368610]

>>7368569
Actually, in the model in my post, then relative to the portals when the cube is halfway through the orange half will be moving towards the orange portal with velocity v, and the blue half will be moving out of the blue portal with velocity v.

But again, this is all pointless without a rigorous model.

I'm assuming

>the principle of relativity
>Weak conservation of momentum: An object should feel no acceleration as it passes through a portal. It leaves one portal with the same velocity (relative to the exit portal) as it entered with (relative to the entry portal).

[Anonymous No.7368617]

The answer is unambiguously B.

The portal physics are really just a red herring to troll your intuition, but all you actually need to be aware of is Gallilean relativity. Look at it in the frame of reference where the piston is not moving, and it becomes as straightforward as can be.

[Anonymous No.7368618]

>>7368609
kek

I hope you account for air resistance in all of your calculations anon

[Anonymous No.7368623]

>>7368617
And still most people think it's A.

[Anonymous No.7368706]

There is no friction between the cube and the plate so there is no transfer of energy.

[Anonymous No.7368710]

>>7368604
>there's no such thing as absolute motion

tell that to light, kid

[Anonymous No.7368717]

>>7368710
>Tell that to light

Huh? I think you may be out of your depth, kid.

[Anonymous No.7368762]

>>7368483
I know this a troll using the multiple ways to interpret technology that doesn't yet exist

but assuming that the portals are attached to the platform with no connection to some other generating device, then applying relativity to it it must be B, with the platform with the portals on it losing some momentum

[Anonymous No.7368798]

>>7368717
I think you maybe didn't understand 1-st year physics.

[Anonymous No.7368823]

>>7368798

Actually I think maybe you don't. But how about you say what you're thinking so we can sort it out. I'm guessing you've heard that the speed of light is constant and conclude that that means there is absolute motion. In fact, it means the exact opposite. But hey, maybe you meant something else! Who knows, if you don't use your words?

[Anonymous No.7368846]

is this a stupid questions thread? couldnt find one so I guess I will post here:

I got admitted to the physics college, I did a math test and ended up on the government budget
I dont know a thing about physics and I sucked at highschool math, some chick that was there that I dont even know solved me whole admission test, now what?

They were taking 40 people on the budget, and student program was called "applied and computer physics" at the college of physics of my country

[Anonymous No.7368848]

>>7368502
shut the fuck up

[Anonymous No.7368852]

>>7368530
Best answer in the thread.

[Anonymous No.7368968]

>>7368569

Well, considering the model doesn't have friction applied and gravity is explicitly said to not exist then A must be the answer.

The process would be equivalent to the object "striking itself" at the same velocity as the platform. Since the vector has it entering the platform at the bottom portal it would balance by exiting the top.

The only way it could "balance" is if friction were involved. I wouldn't think friction is involved with portals and no such friction is defined. Furthermore, the "extra" speed is expected, as we already have knowledge of "perpetual motion" from gravity devices.

[Anonymous No.7368973]

>>7368502

[Anonymous No.7368978]

That image name tho

[Anonymous No.7368985]

>>7368968

See>>7368617

[Anonymous No.7368988]

objectively correct answer

[Anonymous No.7369002]

>>7368988

That was my guess

[Anonymous No.7369005]

>>7368988

No

[Anonymous No.7369027]

>>7369005
Yes

Let's assume it started in that position not moving and then the piston started moving in the direction indicator

The cube would just sit there because of equal forces on both sides

[Anonymous No.7369047]

>>7368483
With A, there is no force keeping the cube from going through the portal.
With B, energy is not conserved.

This is why we can't have moving portals in the game.

Of course, it's possible that the "portals" are just painted on in which case it would be A.

[Anonymous No.7369066]

>>7369027
That's what I was trying to say here >>7368569. But this logic also applies to space itself, so nothing would move in or out of the portals at all and it's the reason portals cannot exist. Basically A would happen because portals cannot exist.

It reminds me of the reason Hawking gave for wormholes being impossible.
https://www.youtube.com/watch?v=sUqxzH0652w

[Anonymous No.7369114]

>>7368483
Like literally everyone in this thread is retarded

I post fractal and conceptual shit here all the time and it's obvious that the momentum of the portal noted in B would keep the assumed product from A from advancing so

TL;DR: Half in both, with a bit of jitter tending towards zero, and you're all a disgrace to your fields

[Anonymous No.7369122]

>>7368988
What I thought at first and I still believe would happen, but then again portails don't exist.

[Anonymous No.7369150]

>>7369114
this bait

[Anonymous No.7369173]

>>7368530
this implies the portals work like a hoola hoop instead of each portal linking to their own universe but still using the same universe (hurr quantum superposition) for the reference frame of the bottom portal the universe would be moving towards it with velocity v and for the top portal the universe would also be moving towards it with velocity v

these two combined would cancel eachother out and you would get A

either way both of these definitions break the universe

[Anonymous No.7369210]

>>7368483
We can model portals in a way that they won't break laws of physics. Just assume that portals only convert energy when something enters them.
For example when you want to push one object though a portal that is below the other, you have to give it some kinetic energy that will be converted to potential energy by portal.
In your pic (assuming the extension arm is much heavier than the box), the answer will be B. The box will move with speed close to double speed of the arm and the arm will slow down a little so the sum of energies and momentums will be conserved (just like in elastic collision).

However these portals will not work like in Portal because object will change its speed while entering portals on different heights.

[Anonymous No.7369394]

>>7369173
EVER SEEN THIS MOTHER FUCKER?

[Anonymous No.7369707]

>>7368539
unless energy is expended by the portals when something passes through it proportional to the energy gained by that something. Or the energy comes from the surface the portal is on, given portals can only be placed on certain surfaces

[Anonymous No.7370286]

>>7369027
but it didnt start in this position
its like saying
>kick a football against a wall
>one half of the ball which touches the wall first will be reflected off the wall
>but it gets pushed by the other half, bith movements cancel out ind it just stops and drops
the portal here is no different from a wall

[Anonymous No.7370324]

>>7368483
It's entering at the same rate it is exiting. Since the relative velocity of entering and exiting the portal must be the same we know it's B.

[Anonymous No.7370363]

>>7368483
the fuck do you need portals for this? You could get pretty much the same thing with a curved piece of pipe

[Anonymous No.7370383]

>>7370363
That doesn't sound right at all, in a curved pipe surely the piece would get stuck in the bottom of the U-bend.

[Anonymous No.7370396]

> image name: troll.jpg