# Portal physics questions

So lets say you and your portal gun together weigh 100kg. you are on a ledge 30km above sea level, and behind you is a wall, on which there is a portal, which is at 90 degrees to the ground. You fall to the earth but make another portal before you hit the ground through which you fall, thus flinging you out of the first portal.

My question is, how many more portals will you have to make to enter orbit?

How long from the second you jump of the ledge will it take before you have entered orbit and returned to your portal which was at 30km above sea level, and what speed will you be going at?

This is assuming that there are no other buildings that you might crash into, and that the earth is uniformly spherical, with uniform gravity.

I havent worked this out, so i dont know for sure that you can build up enough speed, so if it turns out you cant, how high would you need to start off to be able to get into orbit? What is the lowest possible starting point?

More similar questions/puzzles?

Note, some puzzles won't work because the way portals behave in the game breaks energy conservation.

Tags: physics, portal

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### Replies to This Discussion

Oh, and you may want to ignore air resistance for this.
Lol I hope someone figures this out! I would put more effort into this but, for the moment I have absolutely no time! I love portal!
as I'm imagining this scenario, you would fly out of the portal 90 degrees to the ground (on a wall), landing in the sea, 30km below.

Another question:

Two walls are getting closer together. You are in between them. You shoot one portal to either side of you. What happens to you when the walls meet?

you will forever be stuck in an infinite tunnel of portals until the walls separate.

Best guess, it is impossible. Due to the falling speed (which I will call Z speed) changing into distance speed (which I will call X speed), I believe you will get to a point (probably after about 3 portal "flings") where the Z speed will not increase due to terminal velocity and that your X speed is not increasing due to your Z speed not increasing. If gravity and other things was less the to extent that it made terminal velocity faster, you "may" enter orbit.

Also, if the planet was really small, that might help too.

Just my thoughts though, best way to know is by trying it. Anyone got a spare portal gun? :)

You would never reach orbit because you would reach terminal velocity due to air resistance. And your terminal velocity is nowhere near the speed needed to reach orbit.