Barnoulli's principle

[omenofdeath]

Barnoulli's principle states that pressure of static fluid>pressure of moving fluid.So if water is made to rush at a greater pressure than that in the ocean,then the water-pipe will contract such that the water-supply will be stopped,resulting in bursting of the pipe.PLEASE COMMENT.

[insane_alien]

uhh can degibber the question its pretty difficult to understand.

 

oh and its bernoulli not barnoulli. i've just spent the last 3 hours working with it.

 

yes, it does state that moving fluids have less pressure than stationary fluids and is the basics behind why planes fly.

 

for a system you have three parameters(static head, pressure head and velocity head) if you add these up you get a constant for that system. if you change any of the parameter one or both of the others will change to compensate.

 

for what i'm thinking your asking that, if you had a weak pipe in the ocean and pumped water through it at a reasonably high velocity would it be crushed. well, yeah it would be but i don't see how it would burst crack from compression certainly but i don't see it bursting. it wouldn't even be completely crushed there would still be flow but at a reduced rate velocity and a higher pressure.

[John Cuthber]

"the basics behind why planes fly."

The classic explanation of how planes fly must logically be wrong. Stunt planes can be flown indefinitely upside down.

As for "PLEASE COMMENT" how about, this post is in the wrong place and please don't WRITE IN CAPITALS.

As insane alien said a pipe with a fast flowing liquid stream will tend to colapse but the effect is usually small.

[insane_alien]

john, you do raise interesting points but if you look at the air flow over an inverted wing the air going over the side facing the sky(just to avoid confusion) is still going faster than the air going on the other side. this is because the plane flys at quite a high pitch which is necessary to produce lift.

 

yeah the effect is really tiny it would need to be a fabric tube to see any real effects.

[Rocket Man]

bernouli principle to do with air craft is based on the assumption that a pocket of air split by the wing re-joins at the back. has been experimentally proven wrong. it's really only the downwash that counts, kinetic energy moves a large mass of air down with enough momentum to counter the mass of the aircraft. since the mass is so great the energy required is low. (both sides of the wing produce downwash, the underside compresses air while the top-rear creates a low pressure zone pulling air down behind the wing)

 

the bernouli principle expliains the venturi effect.

[ssd]

 

... is the basics behind why planes fly.

 

 

It is an incorrect theory as per NASA. Pls check the following link.

 

http://www.grc.nasa.gov/WWW/K-12/airplane/wrong1.html

[John Cuthber]

Thanks for the link but you are the third person to point out the problem with that theory.

[swansont]

To clarify this: The "packets meet up" part is wrong; I think it's a misapplication of continuity. The Bernoulli principle part of it is not wrong, as it's basically a statement of conservation of energy, and energy is conserved.

[CPL.Luke]

the burnoulli effect counts for a very large portion of an airplanes lift (just look at an airplane flying level). Its just that stunt planes are designed with flying

upside down in mind, so they design the wing to not make use of the burnoulli effect and instead bump up the engine power

 

Modern aircraft can be made to fly without the use of the burnoulli effect and instead rely on directing air downwards in order to maintain lift, however this isn't as efficient as using the burnoulli effect so cargo planes and the like will use burnoulli wings, And military aircraft and stunt planes will use straight wings.

 

 

but the burnoulli effect does play an important role in most aircraft, as can be seen when an aircraft drops altitude by merely slowing down.

[swansont]

Bernoulli and angle of attack are two ways of explaining the same thing. One does so with conservation of energy, the other with conservation of momentum. The difference is in the ease of explanation.

[ssd]

Thanks for the link but you are the third person to point out the problem with that theory.

 

Not taking credit away from anybody, my intention was to inform about the nice page by NASA for those who have not seen it before.