Why Faster Fluids Have Lower Pressure? #VeritasiumContest

#VeritasiumContest

Bernoulli's principle states that the pressure of a non compressible fluid reduces, when its speed increases. This seems weird as we may expect the fluid with more speed to carry more pressure. In this video, let's explore this effect intuitively.

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[srijanrudra]

Great job, finally understood Bernoulli's principle!!

[raffybediones]

I think when the water hits your hand, it has to do with the impulse momentum theory. Where the short amount of time of impact causes a large reaction force, considering the velocity of water is high before the impact. What an intuitive content!

[ohanneskamerkoseyan]

Best intuitive explanation of what's going on under the equations i've seen so far. Thank you very much!

[yoganandpatle]

The thing is pressure or energy is always constant, when fluid accelerate due to narrow passage its static pressure is decreasing which is felt on the wall of the passage and kinetic pressure is increasing,
Overall all pressure is static pressure + dynamic (kinetic pressure) remains constant.

[me_neutron]

Wow! Great video. Nicely explained this concept in a minute.

[morten]

While the molecules in a fluid are constantly vibrating and jostling around, the

average distance between them tends to increase when the flow speed increases. This is especially true in the scenario described by Bernoulli's principle where a fluid is flowing through a pipe with a changing cross-sectional area.

Here's a more detailed explanation:

Constant Speed: In a region of constant cross-sectional area and constant flow speed, the molecules maintain an average distance due to the balance between their kinetic energy (related to their motion) and the intermolecular forces (the forces that attract or repel molecules from each other).

Narrowing Pipe (Increasing Speed): When the pipe narrows, the fluid is forced to speed up to maintain the same volume flow rate. This means the molecules gain kinetic energy.

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Increased Spacing: As the molecules move faster, they tend to spend less time close to each other and more time further apart. This results in an increase in the average distance between them. The increased spacing means fewer collisions between molecules, which leads to a decrease in pressure.
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Important Note: This increase in average spacing is more significant in gases than in liquids. Liquids are much denser than gases, and their molecules are already closely packed together. So while the average spacing might increase slightly in a faster-moving liquid, it's not as noticeable as in a gas.

[bernardocisneros]

Very good presentation to explain Bernoulli's principle.

[saralvigneshwarradhakrishn]

Editor has done a great job showing forces on every side of water

[Rick_Cavallaro]

I know it's impossible to cover everything in one minute, but I thought I'd mention the bit about it feeling like more pressure when it hits your hand...
The Bernoulli effect applies to fluids that we're not doing any work on. And on such flows, the "total pressure" remains constant. This is possible because the static pressure goes down and the dynamic pressure goes up when the fluid accelerates. The static pressure is what you'd measure if you were moving along inside the fluid. The dynamic pressure is what you feel when it hits your hand.

[justlearn]

Holy moly
So happy to see float head physics again

[shenoyroopesh]

Really cool video explaining the Bernoulli principle. Very easy to understand!

[RobertWF]

At a molecular level, faster molecules have fewer "bounces" against the container walls (= lower pressure) since they're traveling a greater distance parallel to the walls.

[shyam]

The way I "feel" this thing is - Imagine the tube is not yet completely filled with water and it is gradually filling. So the continuity equation doesn't hold yet .Now what would happen at the intersection of tube of less area and tube of more area?- more and more water molecule would reach there but won't be able to enter the tube of narrow opening as there is not much space there, so this thing would continue until there are so many molecules accumulated in the wider tube that their pressure becomes so high that it satisfies the continuity equation by increasing the speed of water. You can explain this in resistance terms - the narrower the opening, the higher the resistance.(And this is experimental)

[Name-isbp]

This is a really interesting way to think about it, thanks.

[kevinshen]

I am placing bets that you will win this competition

[familybialousow]

I believe while the pressure might be lower either at the walls of the channel or between fluid molecules, its a misconception that pressure is less in the forward direction. A good way to understand what I mean is, if you placed a detector in the front of your water faucet and shrunk the size of the hole the water has to exit, the detector will most definitely read more pressure since the water gouging out has more force applied towards that direction

[ponselvanarumugasamy]

Omg omg, I finally understand bernouli 😢
Thank you 💗

[chloej]

Perfect explanation! Thank you so so much!

[DANGJOS]

This is a very good video! Concise and very understandable!

[snrnsjd]

Thank you sir!! Great explanation for simple mortals like me.