1. Do Now  Describe each scenario as conduction, convection or radiation: A. A fire warming up someone’s body who is sitting near the fire B. A pot of water heating up on the stove C. Putting an ice pack on a burn D. Light from a lamp shines on you and warms you up. E. Holding a mug filled with coffee to warm up your hands

2. Today’s Agenda 5 min Do Now 5 min Important Dates 25 min First Law of Thermodynamics 20 min Second Law of Thermodynamics 5 min Exit Ticket

3. Today’s Agenda 5 min Do Now 5 min Important Dates 25 min First Law of Thermodynamics 20 min Second Law of Thermodynamics 5 min Exit Ticket

4. Important Dates & Reminders  Homework Turn-In  Last Unit Exam Next Wednesday  Study Guide Tomorrow  Ice Cream Lab TOMORROW!  March Monthly News Project  Due Mon. April 2 nd  US Space and Rocket Center Field Trip  Money and permission slips due Wed. Apr. 4  Nashville College Trip (MTSU, TSU, Belmont)  Money and permission slips due TOMORROW!

5. Today’s Agenda 5 min Do Now 5 min Important Dates 25 min First Law of Thermodynamics 20 min Second Law of Thermodynamics 5 min Exit Ticket

6. The First Law of Thermodynamics basically states that in a closed system, energy can neither be created nor destroyed, only transformed or transferred. There is an energy balance in the universe. What does this sound a lot like??? First Law of Thermodynamics

7. Connection to Heat  Whenever heat is added to a system, it transforms to an equal amount of some other form of energy.  That form of energy is WORK.  Internal energy vs. External energy  Internal energy is the energy stored within in object/system  External energy is the energy outside of an object/system

8.  Some visual examples of this principle Conservation of Energy

9. Another Look at Q Q =  E – W Q = (E F – E I ) -W Q = heat added TO THE SYSTEM  E =  in internal energy W = Work done ON THE SYSTEM If the system does work, W is NEGATIVE

10. Example 1  A total of 135 J of work is done on a gaseous refrigerant as it undergoes compression. If the internal energy of the gas increases by 156 J during the process, what is the total amount of energy removed from the gas by heat?

11. Example 1 Answer  A total of 135 J of work is done on a gaseous refrigerant as it undergoes compression. If the internal energy of the gas increases by 156 J during the process, what is the total amount of energy removed from the gas by heat?  Q = Δ E – W  Q = 156 J – 135 J  Q = 21 J

12. Example 2  An object has an initial internal energy of 48 J. The internal energy increases to 73 J when 38 J of work is done. What is the amount of energy in the form of heat that was lost by the system during this?

13. Example 2 Answer  An object has an initial internal energy of 48 J. The internal energy increases to 73 J when 38 J of work is done. What is the amount of energy in the form of heat that was gained by the system during this?  Q = Δ E – W Q = (E F – E I ) – W  Q = (73 J – 48 J) – 38 J  Q = -13 J

14. Example 3  The internal energy of a system is initially 27 J. After 33 J of heat is added to the system, the internal energy is measured to be 86 J. How much work was done on the system?

15. Example 3 Answer  The internal energy of a system is initially 27 J. After 33 J of heat is added to the system, the internal energy is measured to be 86 J. How much work was done on the system?  Q = Δ E – W Q = (E F – E I ) – W  33 J = (86 J – 27 J) – W  W = 26 J

16. Example 4  The internal energy of a system is initially 45 J. A total of 28 J of energy is added to the system by heat while the system does -31 J of work. What is the system’s final internal energy?  Q = Δ E – W Q = (E F – E I ) – W

17. Example 4 Answer  The internal energy of a system is initially 45 J. A total of 28 J of energy is added to the system by heat while the system does -31 J of work. What is the system’s final internal energy?  Q = Δ E – W Q = (E F – E I ) – W  28 J = (E F – 45 J) – (-31) J  E F = 42 J

18. Complete the practice problems on the Daily Organizer under First Law of Thermodynamics Practice Problems

19. Today’s Agenda 5 min Do Now 5 min Important Dates 25 min First Law of Thermodynamics 20 min Second Law of Thermodynamics 5 min Exit Ticket

20. The entropy of the universe increases in all natural processes and reactions. Entropy is the measure of a system’s disorder. Second Law of Thermodynamics

21.  The entropy, or disorder, of the universe increases in all natural processes.  After cleaning your room, it always has a tendency to become messy again.  This is a result of the second law. To understand disorder more, think about gas in a jar that is suddenly released. What is going to happen?  As the disorder in the universe increases, the energy is transformed into less usable forms

22. Calculating Entropy  When a body absorbs an amount of heat Q from a reservoir at temperature T, the body gains and the surroundings lose an amount of entropy  Positive S: Entropy Increased  Negative S: Entropy Decreased

23. Example 1  A system has 91 J of heat transferred to it raising its temperature 15 C. What was the increase in entropy?

24. Example 2  A system starts out at 56 C. It loses 17 J of heat causing its temperature to decrease to 11 C. What was the decrease in entropy?

25. Example 3  When a system increases its temperature from 14 C to 29 C, its entropy also increases by 9 J/C. How much heat energy was transferred into the system?

26. Example 4  When a system initially at 59 C has 65 J of heat transferred into it, its entropy increases by 14 J/C. What was the final temperature of the system?

27. Complete the practice problems on the Daily Organizer under Second Law of Thermodynamics Practice Problems

28. Today’s Agenda 5 min Do Now 5 min Important Dates 25 min First Law of Thermodynamics 20 min Second Law of Thermodynamics 5 min Exit Ticket