Thermodynamics

The absolute temperature in kelvin is obtained by adding 273.15 to the Celsius temperature.

Linear relation between the Celsius and Fahrenheit scales.

The change in length is proportional to the initial length and the temperature change.

The change in area is approximately twice the linear coefficient times the initial area and ΔT.

• isotropic solid and moderate temperature changes.

The change in volume is proportional to the initial volume and the temperature change.

Heat required to change the temperature of a substance, without a phase change.

Ratio of the heat transferred to the temperature change.

applies during a phase change at approximately constant temperature.

In a thermally insulated system

In an isolated calorimeter, the sum of the exchanged heats is zero.

The product PV is proportional to the amount of gas and the absolute temperature.

For a fixed amount of ideal gas

For a fixed amount of gas, PV/T is conserved between two states.

The mean translational kinetic energy of a molecule is proportional to the absolute temperature.

• monatomic ideal gas.

The root-mean-square speed of the molecules is proportional to the square root of T.

The internal energy of a monatomic ideal gas is (3/2)nRT.

Thermodynamic work is the integral of P dV; at constant pressure, PΔV.

The change in internal energy is the heat absorbed minus the work done by the system.

In an isothermal process of an ideal gas, PV is constant, ΔU=0 and Q=W.

In an adiabatic process of an ideal gas, PV^γ is constant, with γ=C_P/C_V.

The efficiency of a heat engine is the net work divided by the heat absorbed from the hot source.

Carnot efficiency depends only on the ratio of the absolute temperatures of the reservoirs.

• absolute temperatures in kelvin.

The heat flow by conduction is proportional to the area and the temperature gradient.

The radiated power is proportional to the fourth power of the absolute temperature.