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Laws of Thermodynamics

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Laws of Thermodynamics

  1. 1. THERMODYNAMICS AN INTRODUCTION
  2. 2. WHAT IS THERMODYNAMICS? The study of relationships involving heat, mechanical work, and other aspects of energy and energy transfer
  3. 3. LAWS OF THERMODYNAMICS First Law Second Law Zeroth Law Third Law
  4. 4. FIRST LAW OF THERMODYNAMICS
  5. 5. FIRST LAW OF THERMODYNAMICS How does a hot cup of coffee get cold? How does ice melt? How is the 1st law exhibited by a car engine?
  6. 6. FIRST LAW OF THERMODYNAMICS Law of Conservation of Energy “Energy cannot be created nor destroyed”
  7. 7. Visualize a hot cup of coffee that is placed on top of a table. After a few minutes, the coffee gets cold. Is energy destroyed?
  8. 8. Energy was not destroyed. Energy was transferred to the environment.
  9. 9. HEAT HEAT HEAT HOT COOL
  10. 10. HEAT HEAT HEAT COFFEE ENVIRONMENT
  11. 11. CONSERVATION OF ENERGY Another example is a chain of energy transfer that starts with the microwave oven.
  12. 12. CONSERVATION OF ENERGY 1ELECTRICAL energy is converted to THERMAL energy
  13. 13. CONSERVATION OF ENERGY 2HEAT is TRANSFERRED to the food we are cooking
  14. 14. CONSERVATION OF ENERGY 3After cooking, we take out the food out of the oven and expose it to the environment and, thus, HEAT from the food is transferred to the environment
  15. 15. CONSERVATION OF ENERGY 4We get hungry. We eat the food and the CHEMICAL energy in the food is converted to KINETIC energy as we do our daily activities.
  16. 16. CONSERVATION OF ENERGY 5The energy transfer goes on… …Continue the chain
  17. 17. FIRST LAW OF THERMODYNAMICS How does a hot cup of coffee get cold? How does ice melt? How is the 1st law exhibited by a car engine?
  18. 18. FIRST LAW OF THERMODYNAMICS How does a hot cup of coffee get cold? How does ice melt? How is the 1st law exhibited by a car engine?
  19. 19. SECOND LAW OF THERMODYNAMICS
  20. 20. SECOND LAW OF THERMODYNAMICS Why can’t there be a 100% efficient engine? When are you more efficient, when you focus on one thing or when you multitask?
  21. 21. SECOND LAW OF THERMODYNAMICS There is a limit to the availability of energy and the ways in which it can be used or converted No such thing as a 100% efficient engine Follows the concept of entropy (Entropy = energy degradation)
  22. 22. SECOND LAW OF THERMODYNAMICS Imagine that you have a pot with a plant in it. As you were watering it, you noticed grass growing around the plant. How sure are you that the water you are giving is absorbed by the plant alone?
  23. 23. FOLLOWS THE CONCEPT OF ENTROPY Entropy is simply the degradation of energy. Due to the continuous process of energy transfer and conversion, energy is degraded.
  24. 24. FOLLOWS THE CONCEPT OF ENTROPY Let’s play the game “Pass the Message”
  25. 25. WHY CAN’T THERE BE A 100% EFFICIENT ENGINE? Friction Heat is released by the engine etc Heat Mechanical Energy
  26. 26. SECOND LAW OF THERMODYNAMICS Why can’t there be a 100% efficient engine? When are you more efficient, when you focus on one thing or when you multitask?
  27. 27. ZEROTH LAW OF THERMODYNAMICS
  28. 28. ZEROTH LAW OF THERMODYNAMICS Thermal Equilibrium
  29. 29. ZEROTH LAW OF THERMODYNAMICS We leave two cups of coffee (where one is observably hotter than the other) on the kitchen table and we just leave them there. After 30 minutes what will we notice about the two cups of coffee?
  30. 30. They will both cool down and will seemingly both have the same temperature.
  31. 31. ENVIRONMENTHEAT HEAT
  32. 32. ENVIRONMENT
  33. 33. ZEROTH LAW OF THERMODYNAMICS ENVIRONMENT A B C
  34. 34. THIRD LAW OF THERMODYNAMICS
  35. 35. THIRD LAW OF THERMODYNAMICS Possibility of Absolute Zero temperature
  36. 36. THIRD LAW OF THERMODYNAMICS Is it possible?
  37. 37. THIRD LAW OF THERMODYNAMICS It is impossible to reduce any system to absolute zero in a finite series of operations - In order to have an object at Absolute Zero temperature, an abundant amount of matter at Absolute Zero temperature must pre-exist
  38. 38. SUMMARY 4 laws of Thermodynamics - Law of Conservation of Energy - Entropy - Equilibrium - Absolute Zero
  39. 39. HOMEWORK (I WHOLE INTERMEDIATE PAPER) 1. We can notice the tubing system at the back of the refrigerator. Where does the heat of the tubing come from? 2. Why is an air conditioner placed in a window and not on the floor? 3. Could we cool the house if we leave the refrigerator door open?

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