Bernoulli 5

[okiebsooner]

Bernoulli's principle is that as the velocity increases, so does the pressure. The video states exactly the opposite, so it is wrong. The simplified Bernoulli's eqtn is P=4v2, where the velocity is squared and then multiplied by a factor of 4. As you can see, pressure has a direct relationship with velocity. Please don't get misinformed by this video.

[mkl3opt]

Bernoulli's effect? NO.

I believe the basic premise regarding velocity and pressure is wrong in these cases. Wrong explanation to what is really occurring.

[fnairportmovies]

song?

[DoriWP]

GENIALES TODOS LOS EXPERIMENTOS!!

[cliveso]

The blowing across paper thing does NOT demonstrate Bernoulli's principle. If blowing over the top lifts the paper because of the "low pressure", then blowing over the underside must pull the paper downwards. Except it doesn't. Try it -- it's clearly not true...

[HipHopUploadz]

very helpful ! Thanks

[sagabhcrew]

nice, now in case i can visit USA again i know how to spread that thing around neighbors yards and so on)))

[spiralreplicator]

Perfect for halloween papering of trees and houses with the toilet paper guns, Let the fun begin !

[john7epino]

so really good.

[AlJoKo21]

the explanation at 1:35 is wrong. The fluid doesn't move faster, because it "has" to go a longer distance. That sounds like two air particles which start at one end of the frisbee must get together again on the other side. Why should they? The air particle above doesn't know, how fast the air particle below moves. Of coure the air is quicker above. But the explanation is wrong.

[mikrosbobos]

what is the right explanation then? why it goes faster?

[AlJoKo21]

@mikrosbobos Well I gotta say that I don't know why I wrote that :-D ("Of course the air is quicker above"), that's just wrong, sorry.

The right explanation is: The air particles are being directed downwards by the wing. So there is an impulse and therefore (many impulses per period) a force downwards (caused by the air molecules). Due to Newton's actio=reactio there's also a force upwards (representing the uplift). The Bernoulli-Effect is insignificant regarding the uplift.

[identernet]

I do wish people knew the difference between Bernoulli and Coanda. Don't worry your not alone.

[MrMohamed1993]

thx that helped me understand Bernoulli's principle.

[ropaez2001]

Muy ingenioso me gusto el video los felicito yo soy profesor de fisica y matematica en argentina pueden entrar en you tube "profesor paez " y ver la explicacion de estatica y dinamica.

Me causo gracia la ultima parte..ok

[plord28]

what shame. think of all the poor students who could not wipe their ass because somone had already stolen all the toilet paper from the bathrooms :(

[HomoBorealis]

This is just friction. It has nothing to do with Bernoulli. Also check out "equal transit time fallacy".

[number098]

When air pressure from the top decreases due to speed, is there air pressure from the bottom which causes it (frisbee for instance) to go up and if so in what direction is the air pressure from the bottom? If anyone can shed some light, thanks.

[1Flyboy1123]

air has equal pressure in every direction, when the air is rushing over tho top the air pressure decreases so there is greater pressure under the frisbee.

[siouxieblair]

Jeez, is that a rocket in his pocket?

[bekkil5]

What song is this?

[wbeaty]

The frisbee part is wrong.

It's a widespread misconception that air which gets split by an airfoil must rejoin again at the trailing edge. In fact, air only rejoins if the airfoil is adjusted to give zero lifting force! When generating lift, the air DOESN'T rejoin. (Many beginners' books get this point wrong, and so they explain airfoils wrong.)

Don't believe me? Go search "incorrect lift theory" for the NASA page that debunks the misconception. It's called "Equal Transit Time" error.

[wbeaty]

Also search on keywords "Equal transit time fallacy

Air does travel faster over the top of an airfoil. But it travels *way* faster than the air below the airfoil. It travels so fast that the divided air can never rejoin ...and the divided air remains forever split. You can find online wind-tunnel photos which show this process, and physics papers which go into the details.

So, why the difference in speed above? Ah, THAT'S the question. Understand that, and you'll really grasp airfoils.

[matt2virgilio]

I myself when I got this explanation for the first time came up with the simple question: why do the two fluid particle have to meet at the other end? The person who was teaching me actually gave me a reason for it and I believe it for years :(

Thanks for your suggestions: I'll go and read it! :D

[trekgeek1]

@wbeaty

Thank you for doing that. I was going to correct the error, but it was nice having it done already. Plus, you beat my by a year, so you probably saved a lot of people from that mistake.

[gtawhatwhat]

interesting

[domyaska]

bello..grazie

[Hammandy]

Muy interesante. Creo que lo intentaré en clase.

[rherculano]

Bernoulli is the best genie.

[pcbh84]

this does have to do with bernoullis principle. Isnt the fact that paper lifts when you blow over it due to bernoullis principle? That demonstrates the basic concept of lift

[mynameiscaleb]

this is gay and hardly anything to do with flight. wanker!

[mpd19666]

Hey dumbass, It has everything to do with flight. It is the basic principal that explains how airfoils generate lift.

[FizxChick]

While very cool, these are demonstrations of complex air flow, not Bernoulli's principle.

D. Bernoulli was studying the effect on liquids specifically, not fluids in general. His principle is highly idealized and strictly applies to incompressible liquids (air is not incompressible or a liquid) with laminar flow (air is usually turbulent), and no viscosity (no fluid is without viscosity).

(Check any NASA or Air Force website if you don't believe me.)

[mpd19666]

Air can be treated as incompressible below about Mach .8. Also air can be treated as invicid for general calculations at sea level