TcTc QhQh QcQc W ThTh

(a) - piston at room temp and atmospheric pressure P V a Heat Engine Example

(a-b) - gas heated to keep volume constant as cart rolls onto piston P V a b Heat Engine Example

(b-c) - gas heated to increase volume and lift the cart P V a b c Heat Engine Example

(c-d) - gas cooled to keep volume constant at cart rolls off piston P V a b c d Heat Engine Example

(d-a) - gas cooled to reduce volume back to initial level P V a b c d Heat Engine Example

Work done?

W, Q H, Q C, Efficiency, Power

1 st Law Energy is conserved

2 nd Law Impossible to convert heat completely to work i.e. no perfect heat engines

DO DREAMS MATTER? Scott Adams: "Losers have goals, winners have systems." "Success caused passion more than passion caused success." vs. Nathan Pacheco: Give dreams you attention - they aren't going to burn brighter in the future.

Carnot’s big idea A reversible engine works as well backwards as forwards... So no engine operating between two thermal reservoirs can have more efficiency than a reversible engine between the same reservoirs, and all reversible engines will have the same efficiency.

Carnot cycle 1. Isothermal expansion 2. Adiabatic expansion 3. Isothermal compression 4. Adiabatic compression

Carnot Efficiency

Carnot engine Most efficient engine possible:

Perpetual motion machines These machines violate either These machines violate either –Conservation of Energy –2 nd Law of Thermodynamics What is wrong with this picture? What is wrong with this picture? My first million $ Generator Battery

Recycling heat from exhaust

Otto Cycle

COP Refrigerators and Heat Pumps

Why gasoline? “Gasoline stinks. It pollutes the atmosphere with carbon dioxide, and it is blamed for global warming and for nitrous oxides that cause smog. It finances totalitarian dictatorships and terrorists and drives us to war.” – Richard Muller, Physics for Future Presidents

What about Batteries? For the same weight : Gasoline has 100 times the usable energy of the best rechargeable batteries Gasoline has 100 times the usable energy of the best rechargeable batteries