Thermo finals

• The second law of thermodynamics- states that heat will never of itself flow from a cold object to a hot object.
• If a hot brick is next to a cold brick, heat flows from hot brick to the cold brick until both bricks arrive at thermal equilibrium.
• If the hot brick takes heat from cold brick and becomes hotter.
• The first thermodynamics is not violated.
• However this would violate the second law of thermodynamics.
• Second law of thermodynamics- describes the direction of heat flow in the natural processes.
• In winter, heat flows from inside a warm heated home to cold air outside.
• Hot air outside into the cooler interior.
• But only by imposing external effort- as occurs with heat pumps.
• Third law of thermodynamics- no system can reach absolute zero.
• As investigators attempt to reach this lower temperature.
• Physicist have been able to record temperature that have less than millionth of kelvin- but never as low as 0K.
• AC TO SLOT- no heat engine can convert all heat input to mechanical energy output.
• Heat engine- is any device that changes internal energy into mechanical work.
• We picture a high temperature resevoir
• Low temperature resevoir- as something that absorb heat without itself warming up.
• Heat flows out of a high temperature resevoir into the heat engine and then into a low temperature resevoir.
• Increase its internal energy to absorbing heat from a reservoir of higher temperature.
• Convert some of this energy into mechanical work and expel the remaining energy as heat to some lower temperature resevoir.
• Thot- is the temperature of hot resevoir.
• Tcold- is the temperature of the cold.
• Entropy- is the measure of the amount of disorder in the system.
• Work input as in living organisms entropy decreases.
• Entropy spontaneously decreases.
• Thermodynamics- the study of heat and transformation into mechanical energy
• Greek words- movement of heat
• As the thermal motion of atoms in a substance approaches zero/ the temperature of the substance approaches a lower limit.
• At absolute zero no further lowering of its temperature is possible
• This temperature is 273 degrees below zero on the Celcius scale
• Ice melts at 0⁰C or 273K and water boils at 100⁰C or 373K
• As the weight fall they give up potential energy and warm.
• James Joule- first demonstrated for whom unit of energy.
• The First law of thermodynamics - is the law of conservation of energy applied to thermal systems.
• Adiabatic Processes

  When the work is done in a gas by adiabatically compressing it the gas gains internal energy and warmer.
• Adiabatic- When a gas is compressed or expanded so that no heat enters or leaves a system.
• Heat and Temperature

  AIR TEMPERATURE way he changed by adding or subtracting heat by changing the pressure of the air or by both.
• In this case an increase in pressure will cause an increase in temperature and vice versa.
• Change in air temperature- pressure change
• Pressure and Temperature

  Adiabatic processes in the atmosphere occur in large masses of air that have dimensions on the order of kilometers.
• Large masses- air blobs