this post was submitted on 18 Aug 2023
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[–] [email protected] 10 points 1 year ago (2 children)

B) The train transfers momentum to the things that pass through the portal. If it wouldn't, the portal couldn't exist since you need a certain amount of energy to displace the air on the other end.

[–] Goldmage263 4 points 1 year ago (1 children)

I don't agree. Inertia and momentum are not affected by a portal, even a moving one. If so, their legs would be stretched as they were partially through the portal till the body was being jerked away from the neck causing an even greated relative velocity compared to entering the portal.

[–] [email protected] 4 points 1 year ago (1 children)

Let's say the train moves at 100mph, therefore your body needs to exit the other portal at 100mph. Otherwise it would be compressed. What happens to the energy of this movement if you just stop on the other end?

[–] [email protected] 3 points 1 year ago* (last edited 1 year ago) (1 children)

We also need to consider the air that is in front of the train as it moves forward. That air is going into the portal at the rate the train moves forward and therefore coming out the other portal at that rate.

[–] [email protected] 1 points 1 year ago

The air in front of the portal would be pushing into the portal, and the only acceleration on it would come from the air behind it being pushed into the portal and any other air pressure differences between the two sides.

There's no human pressure differences between the two sides of the portal, so there would no be any reason why you would suddenly be launched at 100 mph the way you would should the train have hit you. It would be like a tube or a hula hoop sliding over you at 100 mph.

As long as you don't touch the tube you're fine.

[–] [email protected] 3 points 1 year ago (1 children)

Fun fact, the portal doesn't exist.

[–] [email protected] 4 points 1 year ago

Not with that attitude!