Chapter 9

Solids, Liquids, & Gases

 

Bernoulli's Equation:

 

(11)

Bernoulli's equation states that the sum of the pressure (P), the kinetic energy per volume ()m, and the potential energy per unit volume () has the same value at all points along a streamline.

(12)

 

Example 14

Using the information from the previous example, suppose the pressure in the fire hose is 350 kPa. What is the pressure in the nozzle?

 

Solution:

 

Example 15

Water flows with constant speed through a garden hose that goes up a step 20.0 cm high. If the water pressure is 143 kPa at the bottom of the step, what is its pressure at the top of the step?

 

Solution:

 

Example 16

Repeat the previous example with the following additional information: (a) the cross-sectional area of the hose at the top of the step is half that at the bottom of the step, and (b) the speed of the water at the bottom of the step is 1.20 m/s.

Solution:

 

Torricelli's Result:

(13)

 

Venturi Effect:

Rapidly moving fluids sustain less pressure than slowly moving fluids.

 

Air foils

 

 

On to some more examples