1. CHAPTER 8 - FLUID MECHANICS
UNIT 2 - MECHANICS
CHAPTER 8 - FLUID MECHANICS

2. Chapter 8C Gas Laws

3. Lots of Scientists in this Chapter!!
Guillaume Amontons
John Dalton
Joseph Gay-Lussac
Amedeo Avogadro
Robert Boyle
Jacques Charles

4. Boyle’s Law
States that the volume of a fixed quantity of a confined gas is inversely proportional to its pressure when its temperature is held constant
Formula:
P1V1=P2V2
P=pressure V=volume
Example Problem 8-1 & 8-2 page 171
How is this useful??
Compressed air?

5. Charles’s Law
States that the volume of a fixed quantity of a confined gas is directly proportional to its absolute temperature when its pressure is held constant
Formula:
V1/T1 = V2/T2
V=volume T=temperature in Kelvin!
How do we get Kelvin from Celsius??
Example Problem 8-3 page 173

6. CHAPTER 9 THERMODYNAMICS
UNIT 2 MECHANICS
CHAPTER 9
THERMODYNAMICS

7. CHAPTER 9B TEMPERATURE

8. Thermometric Properties
Who determines whether you are hot or cold?
Those terms are subjective, scientists need something objective to measure temperatures
Temperature
A measure of the average kinetic energy of the particles in a substance
The hotness or coldness of an object, measure in degrees
Change depends on temperature scale
Thermometer
An instrument that uses a thermometric property to measure and display temperature

9. Temperature Scales
Scientists needed a way to make sure that the whole world was using the same scale to record temperature
Fiducial point
Fixed, precise, and easily reproducible values in a dimension used to calibrate a measuring scale
Examples: boiling and melting points

10. Temperature Scales Fahrenheit scale
A temperature scale with fiducial points at the freezing point (32) and boiling point (212) of pure water at 1 atm of pressure
Mercury verses alcohol based?
180o difference between melting and boiling point
Daniel Gabriel Fahrenheit

11. Temperature Scales Celsius scale
A temperature scale with fiducial points at the freezing point (0) and the boiling point (100) of pure water at 1 atm pressure
100o difference between melting and boiling point
Anders Celsius
Decimal scale
Most of the world uses this scale, not the US
Two formulas for conversions:
Tc= 5/9(Tf+40)-40
Tf=9/5(Tc+40)-40

12. Temperature Scales Kelvin scale Easy formulas for conversion:
The absolute temperature scale, whose theoretical zero point is absolute zero
No degree signs
Single fiducial point is the triple point of pure water (273.16)
The pressure and temperature conditions at which the solid, liquid, and gaseous phases of a substance simultaneously exist in a stable condition
Easy formulas for conversion:
Tk=Tc
Tc=Tk

13. CHAPTER 9C HEAT

14. Facet page 199 Second Law of Thermodynamics Entropy
Law stating that every natural process proceeds toward a condition of lowest usable energy and highest entropy
Entropy
The measure of a system’s randomness of disorder
Greater entropy = greater disorder

15. Heat Transfer Heat Occurs through one of three processes
A quantity of thermal energy that flows from one system to another
Occurs through one of three processes
Conduction
Convection
Radiation

16. Conduction
The flow of thermal energy from a hotter to a cooler object by direct contact
The flow of an electrical current through a conductor
A material through which heat and electricity easily flow
Usually materials that contain mobile electrons, such as most metals
Wants to reach a thermal equilibrium
The condition of a system that is at the same temperature as its surroundings so there is no net flow of thermal energy
Chief process by which thermal energy moves through solids

17. Convection
The transfer of thermal energy from one location to another through the movement of matter
Thermal energy transfer between fluids
Natural convection
Occurs under the influence of gravity
Convection current
A flow of matter in a fluid as warmer, lower density fluid is displaced upward by cooler, denser fluid flowing downward
Cyclical path
Only occurs in a gravitation field
Forced convection
Atmospheric convection

18. Radiation
Nuclear particles or electromagnetic waves that radiate away from their sources
A method of heat transfer through radiant (electromagnetic) energy
What should you wear on a hot day, a black shirt or a white one?

19. Insulation & Thermal Resistance
Insulators
A material that does not easily conduct thermal energy or electricity
Poor conductors with tightly bound valence electrons
What is the particle difference between conductors and insulators?
Aerogels
The best artificial insulators
Facet page 194

20. Heat Capacity
Every object has a particular relationship between the amount of thermal energy absorbed and the temperature change experienced
Heat capacity
The amount of thermal energy an entire object must gain or lose to change its temperature 1oC
Depends on the mass and thermal properties of the substance(s) in the object
Formula:
C=Q/ t
C=heat capacity Q=thermal energy T=temperature in Celsius

21. Specific Heat Capacity
The amount of thermal energy 1g of a substance must gain or lose to change its temperature 1oC
Calorimeter
A device that measure thermal energy transfer between objects contained in a chamber insulated from its surroundings
Formula:
Q=mcsp t
Example Problem 9-1 page 196

23. Heat and Phase Changes Latent heat of fusion (Lf)
The amount of thermal energy absorbed per gram as a solid melts (fuses) at its melting point
The same amount of heat per gram must be released to freeze the substance
Formula: Q=mLf
Latent heat of vaporization (Lv)
The amount of thermal energy absorbed per gram as a liquid vaporizes
The same amount of heat per gram must be release to condense the vapor to a liquid
Formula: Q=mLv