1. T HE FOUR LAWS OF T HERMODYNAMICS Prepared by: VAGHASIYA JAYDIP RAMANIKBHAI (120590119105)

2. T HE FOUR LAWS OF T HERMODYNAMICS The 0 th Law (discovered 4 th ) The 1 st Law (discovered 2 nd ) The 2 nd Law (discovered 1 st ) The 3 rd Law (discovered 3 rd )

3. T HE 0 TH L AW If: Objects A and B are the same temperature Objects B and C are the same temperature Then: Objects A and C are the same temperature Just the transitive property of mathematics.

4. 1 ST L AW OF T HERMODYNAMICS The total sum of all energy in an isolated system will never increase or decrease. “Law of conservation of energy.” Energy cannot be created or destroyed, only transfer forms.

5. 2 ND L AW OF T HERM. If two objects are not the same temperature then: Heat will always flow from high to low temperatures. o Hot object will decrease in temperature and cold object will increase in temperature until they are both the same temperature.

6. 2 ND L AW OF T HERM. Entropy is randomness, i.e., disorder, spread out, lack of structure, messiness, etc. Entropy must increase (unless controlled by an intelligence). Means that: Machines cannot be 100% efficient. Heat flows from hot to cold.

7. N EW I DEA “S” is for “Entropy” S = Q/T Internal Energy / Temperature (absolute) Joule/Kelvin

8. W HAT IS GOING TO HAPPEN ? This system starts with same pressure and temperature on both sides. Then heat is applied to the left side. Which way will the boundary move? (What happens to the pressure on the left side when heated?)

9. W HAT IS GOING TO HAPPEN ? The boundary will move, and temperatures and pressure will even out. 2 Actions: Increasing left pressure will push the boundary towards the right until pressures are the same. At the same time, the unequal temps will affect each other until they are equal.

10. Entropy is a measure of disorder. In this low entropy state, there will be a net force, since there is more movement to the right than to the left.

11. Operating principle of a steam engine. Some of the heat in the hot gas was turned into work done on the cold gas.

12. Q UESTION Can I get any more work out of these gasses?

13. Q UESTION I would need to find a third gas sample at a lower temp to get more useful work. Or supply my own energy to create another temperature difference.

14. Entropy is a measure of how evenly spread out the energy is. Entropy is a measure of energy that is no longer “useful,” or “workable.” Work is change in energy. It won’t change anymore if it’s spread out evenly. (Work won’t change anymore if the temperature is spread out evenly.)

15. M ORE EXAMPLES OF ENTROPY Entropy is randomness. Which is more random? A or B? AB

16. M ORE EXAMPLES OF ENTROPY 2 nd Law of Therm. says that nature always goes from order to disorder. AB

17. M ORE EXAMPLES OF ENTROPY In nature, do you move from A to B or B to A? AB

18. M ORE EXAMPLES OF ENTROPY 2 nd law says that nature always, always moves from A to B and never from B to A. AB

19. M ORE EXAMPLES OF ENTROPY On the large scale, the ice “looks” more disordered. On the small scale, the solid phase severely limits where the molecules could be. The ice crystal molecules are much more ordered than the free moving liquid water molecules.

20. 3 RD LAW OF T HERMODYNAMICS “Absolute zero” is a state of zero motion. This means absolutely no entropy. So it can’t be reached.