Low pressures at high velocities

[Jewish_Vulcan]

Why does pressure decrease as velocity increases, I think it is because pressure is defined as particles hitting the edge of the medium so when velocity increases the particles hit the edge of the medium less but how?

 

[timeslip]

It is called the Bernoulli's effect or principle and is to do with the conservation of energy. If speed increases then pressure has to decrease so the total energy remains the same.

 

[Chestermiller]

Why does pressure decrease as velocity increases, I think it is because pressure is defined as particles hitting the edge of the medium so when velocity increases the particles hit the edge of the medium less but how?

This is an F = ma (Newton's Second Law) kind of thing. If the velocity is increasing, then the fluid is being accelerated. In order to accelerate the fluid, you need to apply a higher pressure (force per unit area) upstream than downstream.

Chet

 

[Jewish_Vulcan]

This is an F = ma (Newton's Second Law) kind of thing. If the velocity is increasing, then the fluid is being accelerated. In order to accelerate the fluid, you need to apply a higher pressure (force per unit area) upstream than downstream.

Chet

ok thank you, I was thinking that but could not really visualize it, I guess sometimes you just have to trust equations even if they do not make sense...