Physics Concepts

Thermal energy represents the total internal energy of an onject, the sum of its molecular kinetic and potential energies.

Kinetic theory relates the average kinetic energy of the molecules in a gas to the temperature of the gas in Kelvins.

First Law of Thermodynamics: ∆U = W + Q Where W is the work done ON the system

• Thermodynamics Processes:
• Adiabatic process: Q = 0
• Isovolumetric (isochoric) process: W = 0
• Isothermal process: ∆U = 0
• Isobaric process: ∆U = W + Q

On a PV diagram, if cycle is clockwise the system is a heat engine and the net work is nagative. If the cycle is counter clockwise the system is a refrigerator and the net work is positive.

Carnot cycles involve only isothermal and adiabatic processes. To determine the efficiency use the Kelvin temp. of the resevoirs.

• Second Law of Thermodynamcis:
• Heat flows naturally from an object at a higher temperature to one of a lower temperature.
• All natural systems rend toward a state of higher disorder (entropy)