1. Heat engines and the laws of thermodynamics Fire? Stop drop and work!

2. Video Given the video we just watched write down – something interesting – Evidence of something we talked about in class

3. First law of thermodynamics Energy can never be created or destroyed (conservation), but it can be transformed. The change in thermal energy of an object is equal to the heat added to the object minus the work done by the object ORΔU = Q - W

4. A heat engine!

5. What this means Lets take a normal car engine as an example: As we pull heat from the exploding gas we get work out of the engine. But it doesn’t all go to driving the car. Ever feel a hood? Or the gas coming out of the exhaust pipe?

6. What it means pt 2 That heat you are feeling is lost heat from the system, it was not converted to work. So the engine is working continuously there is no change in the internal energy. (ΔU=0) Therefore the work done by the engine is W = Q H -Q L

7. How we can use this! This means that when we take a source of heat we can extract ‘work’ from the system. What are some different ways we extract work from heat?

8. Lets try it out We have a heat source that gives out 500 J of work with a thermal change of 1000J. What is our heat?

9. Using an engine A closed engine uses a 1000J source of heat and only lets out 300J of heat loss, how much work is done by the system?