1. Thermodynamics!

2. Heat Heat is the transfer of energy between two objects.
It is an electromagnetic wave when in the radiant form; otherwise the vibrations of the atoms and molecules transfer heat as internal energy.

3. Units of Heat The official SI unit is the Joule (J)
Heat calorie (cal) = J
Kilocalorie (kcal) = 4186 J
Food Calorie (C) = 4186 J
British thermal unit (btu) = 1055 J
Therm = 105,500,000 J

4. Temperature and Energy
When objects receive or lose heat their temperature changes and the internal energy changes.
Types of Internal Energy
A) Translational
B) Rotational
C) Vibrational

5. Movement of Heat
First thing you need to remember is that there is NO such thing as COLD, only a lack of heat
Temperature is the measurement of the average kinetic energy of the molecules of a substance
Heat always moves from “warm to cold” meaning from something with a higher temperature to something with a lower temperature

6. Thermal Equilibrium
When two or more substances of different temperatures are mixed or combined, the heat from the warmer object will move to the cooler object until the temperature of both are balanced.
The temperature at Thermal Equilibrium will be lower than the initial of the warmer object and higher than the initial of the cooler object.

7. Temperature Conversions
There are three equations for temperature conversions that are important to know in this section.
TF = 9/5 Tc
Tc = 5/9(TF )
TK = TC

8. Independent Practice °F to °C °C or °F to K 50 °F °C to °F 10 °C 25 °F

9. Answers °C to °F 27 °C = 81 °F 87 °C = 190 °F 2 °C = 40 °F
°F to °C
50 °F = 10 °C
25 °F = °C
88 °F = 31 °C
-5 °F = °C
0 °F = °C
°C or °F to K
10 °C = 300 K
10. °F = 260 K
25 °F = 270 K
50 °C = 300 K
75 °C = 350 K

10. Heat Transfer

11. Convection
The transfer of heat through the movement of liquids and gases
Ex: turbulence, climate changes, wind, boiling water
Hot water rises, cools, and falls.
Heated air rises, cools, then falls. Air near heater is replaced by cooler air, and the cycle repeats.

12. Ocean Convection Currents Thermal Image

13. Ocean Convection Currents

14. Sea Breeze
Solar radiation reaching the earth causes the land to warm which in turn warms the air (atmosphere) above the land.
Due to greater density, land masses warm faster than bodies of water. Air above the land warms faster, rises, and pulls cooler air from over water onto the land, creating what is called an on-shore (sea) breeze.

15. Offshore Breeze
When the water adjacent to a land mass is warmer, air above the water warms faster, rises, and pulls air above the land off the shore. This is called an off-shore breeze.

16. Conduction
The transfer of heat through touch (direct contact)

17. Radiation
The transfer of heat through electromagnetic waves

18. Calculating the Sun's Temperature
What is the Sun's temperature? (Assume the Sun's emissivity (e) is 1.)
Distance from Sun to Earth: R = 1.5 x 1011 m
Area of sphere of radius R = 4πR2 H = 1000 x 4πR2 = 2.83 x 1026 J/s
Radius of the Sun = r = 6.9 x 108 m
Surface area of the Sun = A = 4πr2 = 5.98 x 1018 m2
esAT4 = H s = 5.67 x 10-8 SI units T = [H/(esA)]1/4 = 5375 K

19. Specific Heat Every substance has a unique specific heat capacity (Cp)
The specific heat is the amount of energy required to raise 1 g of a substance 1 °C
The amount of energy to raise or lower the temperature of a substance
Q = mCpΔT

20. Latent Heat The heat required during a phase change.
Q = mLf/v (fusion or vaporization)

21. Thermodynmaics the study of heat and how it is used to do work.
The internal energy of a substance can be used to do work.
Heat and work can be transferred to or from a system.

22. Work
Specifically, we are going to look at the work done by a gas.
W = -PΔV
P – Pressure (Pa)
ΔV – change in volume (m3)
When work is done by (does, expand) the system the work is negative (losing energy).
When work is done on (compressed) a system work is positive (gaining energy).

23. The First Law of Thermodynamics
U = Q + W
U – Internal Energy
Q – Heat
W – Work
Unit for all is J
Energy is conserved
When heat is added, Q is positive
When heat is removed, Q is negative

24. Types of Thermodynamic Processes
Isovolumetric – the volume of a system remains constant
If ΔV = 0, then W = 0
If W = 0, then U = Q

25. Types of Thermodynamic Processes
Isothermal – The temperature of the system remains constant
ΔU = 0
Adiabatic – no energy is transferred to or from the system (happens very quickly)
Q = 0 , ΔU = W

26. The Second Law of Thermodynamics
No cyclic process that converts heat into work is 100% possible.
When energy is used to do work, some energy will always be turned into unusable heat that is lost to the universe
Entropy – the measure of randomness or disorder of a system (S)
The entropy of the universe is always increasing.