# Bernoulli’s Principle

### Bernoulli’s Principle

Bernoulli’s Principle states that as the speed of a moving fluid (liquid or gas) increases, the pressure within the fluid decreases.

### Venturi Effect

The Venturi effect is the fluid pressure that results when an incompressible fluid flows through a constricted section of a pipe.

Experiment 1

Figure above shows that when water flow from left to right, the water level decreases from left to right. This indicates that, the water pressure decreases from left to right.

Explanation:
Liquids flow from places with higher pressure to places with lower pressure.

However, if the experiment is repeated by using a Venturi tube where the diameter at B is made smaller than A and C as in the diagram above, the water level become lowest at B.

Explanation:
The pressure at B is the lowest because the liquid flow the fastest at B. According to Bernoulli’s Principle, the faster the water flow, the lower the water pressure.

Experiment 2

Figure above shows some air is blow through a tube from left to right. The water level in the capillary tube increases from left to right.
This indicates that the pressure in the tube decreases from left to right.

Explanation:
Gases flow from places with higher pressure to places with lower pressure.

However, if the tube is replaced by a Venturi tube, the water level become highest at B. This indicates that, the pressure of the air is the lowest at B.

Explanation:
The pressure at B is the lowest because the gas flow the fastest at B. According to Bernoulli’s Principle, the faster the gas flow, the lower the gas pressure.