system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What should be long: the distance for taking off or the distance for landing a plane.

Assuming you need to build 2 diffrent traks, one for landing your plane and the other one for taking off, and you have to use a little land as possible. What should be longer, the landing trak or the taking off trak?

Thanks :)
gpt
Take-off is longer. The plane is heavier and fighting against both gravity and drag. A landing plane is lighter due to having burned fuel and benefits from both gravity and drag, so it can lose the speed faster than a plane taking off can accelerate to it. On the other hand, landings aren't always pinpoint accurate, so you do need a safety margin. Even moreso since you need to have a run-off area as well, and space to facilitate aborted landings (so you can't have a cliffside right at the end of the landing runway). Modern airports have pretty much optimized this: a single runway with the necessary run-off areas is also long enough to facilitate takeoffs of planes, so building two of these means you can keep operating even if one is out of commission, but building one solely for takeoffs and one solely for landings means if one is out, the airport is out of the game. If you wanted to minimize ground usage, you would use the catapult-takeoff and wire-landing systems aircraft carriers do, but those are not efficient on land since they use a lot of energy, need a lot of maintenance to remain safe and reliable, and are uncomfortable to passengers.