# How does changing the speed of a fluid affect its pressure?

##### 1 Answer

Hi, sorry for having kept you waiting,

A fluid is either a gas or liquid, right?

**For a liquid in a tube**( like crude oil in a pipeline, or so)

The relationship between Pressure of the liquid and the velocity of flow of its volume, can be written using Bernoulli's equation;

where,

Bernoulli's equation is got from the assumption that, " *total energy per init mass of a liquid flowing* in a pipe or a tube *is constant* "

That is,

*(and i'll spare us of the details... unless requested)*

From the above relation, if

we have,

This also means,

This implies that if

Finally, this means that *there is like* an inverse proportionality relationship between Pressure

**For a gas**(an ideal gas inside a closed container for the matter)

You can simply use the formula

So increasing the speed of the molecules(by heating for example) will increase the rms and hence the Pressure P.

An also, Bernoulli's equation concerns gases too.

It predicts that, for a moving fluid(such as air) the higher the speed of the gas, the smaller the pressure it exerts.