FIRST LAW OF THERMODYNAMICS

1. FIRST LAW OF THERMODYNAMICS

2. Heat Loss, (W) Mechanical Work Out Motor Electrical Power Input (W) m z

3. Adiabatic work Work Transfer System Adiabatic Boundary Surroundings

4. Equivalence of adiabatic processes State 1 Any adiabatic path can be used to connect the two states, and all adiabatic paths between the states will require the same amount of work transfer. State 2

5. First Law Statement • The adiabatic work done on • a closed system to connect • two equilibrium states • is independent of path.

6. The First Law Work done by the system is positive by convention.

7. Internal energy, U Work done by the system is positive by convention. DKE1-2 = 0, and DPE1-2= 0.

8. The First Law of Thermodynamics State 1 Experimentally base, and never refuted by experiment or theory. State 2 Adiabatic Processes

9. Key concepts and terms Adiabatic Work Transfer Total Energy, E Expansion Process First Law of Thermodynamics Internal Energy, U Path independence Quasistatic process Shaft Work