The reason this is so confusing with different answers is that the portals don’t really exist, so inherently whether you say a or b is gonna depend on assumptions. In game they aren’t allowed to move so we have nothing to base it on to match game physics.
Here’s my take, momentum is a product of velocity. Velocity needs a reference frame. Without it, there’s no real difference in saying the portal has a velocity of 0 and the people tied up have a the velocity and therefore momentum, or the other way around. If we assume velocity with respect to the portal is what matters and is the momentum carried forward, then it should be B. If it’s relative to the earth or tied up people, then A.
it’s relative to the earth or tied up people, then A.
If it is relative to the earth, they would be crushed at an atomic level.
Imagine the trolley-portal is passing around a tape measure at 10m/s. The tape measure is stationary on the earth. After 10 seconds, 100m of tape has entered the portal in a straight line. For me to have 100m of tape in a straight line at the exit, the end of the tape has to be moving away from the portal at 10m/s. Given that “crushed into a singularity” is not an option, we can assume the velocity cannot be relative to earth, and must be relative to the portal.
If portals did not apply a transient vector to your momentum then you could not pass through a portal.
Take for instance the many times Chell jumps through a portal. Her momentum is maintained as she passes through the portal, allowing her and her robot legs to do truly stupendous feats of gravity assisted acrobatics.
If Chell was stationary and the portal fell on her, she would not be launched out of the other side with the momentum of the portal, she would just find herself sticking out of the other side of the portal.
Similarly, if Chell were to ride a moving platform up into an overhead portal, we would expect the top half of Chell’s body to pop out of the portal without being accelerated by anything other than the moving platform on the bottom of her feet.
Therefore, unless there is some strange unknowable physics that we will not be able to discover until we develop portals of our own, the most likely outcome is that the victims on the tram would not gain any momentum as the portal was pushed into them, and they would plop out safely on the other side.
The only speed that should be relevant is the object’s speed relative to the portal. Anything else is a distraction. The physics don’t care if you are hurtling at it or it is flying at you, both scenarios are equivalent. The only way to maintain conservation of momentum is to assume your exit speed relative to the exit portal equals your entrance speed relative to the entry portal.
If it did work the other way, well it wouldn’t assuming your exit speed is equal to your initial speed, relative to the exit. That means your speed is 0 as you “exit.” This leaves us with two possibilities. Either you are smashed into a 2d plane and physics gets very concerned, likely forming a teeeeeny tiny black hole. Or the incoming matter behind the first bits will push the first layers through, which, will just wind up back at the starting point, as they will cascade into each other at a speed defined by the speed of the blue portal, being indistinguishable from the projectile interpretation.
The reason this is so confusing with different answers is that the portals don’t really exist, so inherently whether you say a or b is gonna depend on assumptions. In game they aren’t allowed to move so we have nothing to base it on to match game physics.
Here’s my take, momentum is a product of velocity. Velocity needs a reference frame. Without it, there’s no real difference in saying the portal has a velocity of 0 and the people tied up have a the velocity and therefore momentum, or the other way around. If we assume velocity with respect to the portal is what matters and is the momentum carried forward, then it should be B. If it’s relative to the earth or tied up people, then A.
If it is relative to the earth, they would be crushed at an atomic level.
Imagine the trolley-portal is passing around a tape measure at 10m/s. The tape measure is stationary on the earth. After 10 seconds, 100m of tape has entered the portal in a straight line. For me to have 100m of tape in a straight line at the exit, the end of the tape has to be moving away from the portal at 10m/s. Given that “crushed into a singularity” is not an option, we can assume the velocity cannot be relative to earth, and must be relative to the portal.
If portals did not apply a transient vector to your momentum then you could not pass through a portal.
Take for instance the many times Chell jumps through a portal. Her momentum is maintained as she passes through the portal, allowing her and her robot legs to do truly stupendous feats of gravity assisted acrobatics.
If Chell was stationary and the portal fell on her, she would not be launched out of the other side with the momentum of the portal, she would just find herself sticking out of the other side of the portal.
Similarly, if Chell were to ride a moving platform up into an overhead portal, we would expect the top half of Chell’s body to pop out of the portal without being accelerated by anything other than the moving platform on the bottom of her feet.
Therefore, unless there is some strange unknowable physics that we will not be able to discover until we develop portals of our own, the most likely outcome is that the victims on the tram would not gain any momentum as the portal was pushed into them, and they would plop out safely on the other side.
The only speed that should be relevant is the object’s speed relative to the portal. Anything else is a distraction. The physics don’t care if you are hurtling at it or it is flying at you, both scenarios are equivalent. The only way to maintain conservation of momentum is to assume your exit speed relative to the exit portal equals your entrance speed relative to the entry portal.
If it did work the other way, well it wouldn’t assuming your exit speed is equal to your initial speed, relative to the exit. That means your speed is 0 as you “exit.” This leaves us with two possibilities. Either you are smashed into a 2d plane and physics gets very concerned, likely forming a teeeeeny tiny black hole. Or the incoming matter behind the first bits will push the first layers through, which, will just wind up back at the starting point, as they will cascade into each other at a speed defined by the speed of the blue portal, being indistinguishable from the projectile interpretation.