Veritasium
4 HN recommenders · recommended in 4 months, 2013–2026
7:23 · 5M views · Oct 30, 2012
Veritasium explains how trees lift water from roots to the top of tall trunks, using transpiration pull and the negative pressure that liquid water can sustain. It explains why trees do not need pumps or valves.
HN commenters recommend it as one of Veritasium's best videos and one that has aged well.
5 comments from Hacker News
> all it should take is a system of valves, That would work, but it's not how to works apparently. According to this veritasium video, it's because of "negative pressure" aka tension. this video I recommend watching, I think it's one of the best veritasium Dereck has ever produced.
Just recently watched a Veritasium video on how trees get water from the roots to the top of the tree, and it's pretty awesome: this video
this video It's an old video, more than ten years ago, but it aged well IMHO. I re-watched it and re-learned things I have forgotten.
This is an interesting video with an alternate explanation - the pressure required to get water to the top of the tree. Normally you can only suck a water column up 10 meters, and that's using a perfect vacuum - but trees can grow higher than that. The secret sauce is that in a liquid rather than a gas, you can have a negative pressure. this video
... May we have the solution to the questions, also? I went through the concours too but I am very rusty. See also Veritasium on that topic: this video