Fluids
Chapter 11
1. Kinetic Theory of Matter
a. Matter is made of small particles
b. Particles move randomly
c. Collisions are elastic
d. Cohesive forces hold particles together.
2. The Mole
a. Avogadro: Equal volumes of gases have equal numbers of particles
b. Cannizaro: Molar masses of substances have same numbers of particles
c. 6.022x102 particles
3. Fluid
a. Matter that flows
b. Density (m/V) determines behavior
c. Specific Gravity: density substance /density water
4. Pressure
a. Perpendicular force on object by a fluid
b. Average energy transferred by elastic collision
c. P=F/A
d. Unit: Pascal (Pa=Nm)
e. Standard: 1 atm = 101 kPa = 760mm Hg
5. Relationship of Pressure
a. Gravitational Force
b. Collisional foces
c. P2 = P1 +rgh
d. Affected only by height difference
6. The Hoover Dam
a. Example 3
b. Page 314
7. The Swimming Hole
a. Example 4
b. Page 314
8. Blood Pressure
a. Example 5
b. Page 315
9. Measurement of Pressure
a. Pressure moves fluid
b. Pressure moves spring
c. Movement determines pressure
10.Pascal
a. Closed system
b. Pressure same throughout
c. External force produces same pressure
11.Hydraulic System
a. Multiplies force
b. Pressure same in all parts of system
c. Small tube: P=F1/A1
d. Large tube: P=F2/A2
e. F1/A1=F2/A2
f. F2 = F1A2/A1
12.Hydraulic Lift
a. Example 7
b. Page 318
13.Definitions
a. Buoyancy: apparent loss if weight of object in fluid
b. Buoyant Force: net upward force of fluid on object
c. Displaced Volume: volume of fluid equal to submerged volume
14.Archimedes Principle
a. An object is buoyed up by a force equal to the weight (mg) of displaced fluid
b. The object floats if this force is greater than the object's weight
c. Fw = Fb = rVg
d. Depth has no effect
15.Density and Buoyant Force
a. V and g constant
b. P only variable
c. Object sinks if r greater than fluid p
d. Object suspended if r equals fluid
e. Object floats if r I'd less than fluid
16.Control of Density
a. Change Volume
i.Expand lungs
ii.Life jacket
iii. Swim Bladder
b. Change mass
i.Water in ballast tanks
ii.Crocodile swallows rocks
17.Types of Flow
a. Steady: all particles at a point have same speed
b. Unsteady: particles have variable speeds
c. Turbulent: erratic changes due to obstacles
18.Fluid Flow: Density
a. Compressible
i.Constant density
ii.Normal for liquid
iii. Tend to be steady
b. Incompressible
i.Density may vary
ii.Normal for gases
iii. Tend to be unsteady
19.Fluid Flow: Viscosity
a. Non-viscous
i.Flows unhindered
ii.Does not dissipate energy
b. Viscous
i.Viscosity hinders flow
ii.Dissipates energy
20.Ideal Fluid
a. Incompressible
b. Nonviscous
21.Fluid Flow: Rotation
a. Non-rotational
i.Only translational motion
ii.Velocity same across stream
b. Rotational
i.Rotational and translational movement
ii.Velocity varies across stream
22.Continuity of Flow
a. Mass flow (rvg) through tube is constant
b. Only 1 entrance and exit
c. With incompressible fluid reduces to Av
d. Inverse relationship between A and v
23.Effects of Bernoulli’s Principle: Roof in the Wind
a. Air faster over top of roof
b. Pressure over roof lower
c. Pressure inside blows roof off
24.Effects of Bernoulli’s Principle: Baseball
a. Spin increases speed of air on one side
b. Pressure decreases on that side
c. Ball pushed in that direction
25.Effects of Bernoulli’s Principle: Flight
a. Wing more curved on one side
b. Air moves faster on that side
c. Pressure drops
d. Wing pushed toward lower pressure
26.Effects of Bernoulli’s Principle: Submarine Flight
a. Density set equal to seawater
b. Control surfaces shaped like wings
c. Flow of water over surfaces creates lift
d. Changing attitude of control surface changes direction of lift
27.Effects of Bernoulli’s Principle: Plumbing
a. Traps prevent backflow of gases
b. Draining water lowers pressure in pipe
c. Air equalizes pressure so some water stays in pipe