1. Fluid Motion

2. Pressure Pressure – Force/Area Units – pascal (Pa) In fluids
Alternate Units – psi, in Hg, mb, atm, torr
In fluids
Molecular collisions giving a change in momentum.
Direction is normal to the surface
Pressure change perpendicular to equi-potential surface due to gravity. P0 P1 P2 P3 P4 mg

3. Hydrostatic Equation Newton’s law in the vertical Hydrostatic Equation
z = 0 P0 PT P1 P2
z = -h PL PR
Hydrostatic Equation P3 mg P4 PB

4. Grand Coulee Dam
What is the pressure at the base of Grand Coulee Dam which is 150 m deep?
Notice the difference between absolute pressure and gauge pressure.

5. Archimede’s Principle
Any body submerged in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the body.
A 1 kg block of balsa wood is floating in the water. What volume of the block is floating above the water? B mg
(balsa = 120 kg/m3)‏

6. Continuity Equation
For an incompressible fluid, the flow rate (kg/s) through a closed system is constant.
Dl2
Dl1 A1 A2 v2 v1 t1 t2 t1 t2

7. Ideal Fluid Nonviscous - No internal friction
Steady - Velocity at each point remains constant
Incompressible - Density remains constant
Irrotational - No angular momentum about a point within the fluid
A)‏
B)‏
C)‏

8. Bernoulli’s Equation Start with Work-Energy Theorem
Sum of the pressure, kinetic energy/volume, and potential energy/volume is constant along a streamline.
(P2, v2, y2)‏
(P1, v1, y1)‏

9. Water Pressure
Water flows from a 20 m tall water tower to a shower located on the 2nd floor (5 m). What is the velocity of the water leaving the shower?
20m 5m