11 Thermal Physics Flashcards
Absolute scale (Thermal)
- Temperature scale in Kelvins
- defined in terms of absolute zero, 0K,
- and the triple point of water, 273.16 K, which is the temperature at which ice, water and water vapour are in thermal equilibrium.
Absolute zero
- The lowest possible temperature;
2. The temperature at which an object has minimum internal energy.
Absolute temperature T
in kelvin = temperature in degrees Celsius + 273(.15)
Boiling point
The temperature at which a pure liquid at atmospheric pressure boils.
Celsius scale
- temperature, in degrees Celsius,
- is defined as absolute temperature (in Kelvins) minus 273.15.
- This definition means that the temperature of pure melting ice (ice point) is 0 degrees C,
- and the temperature of steam at standard atmospheric pressure (steam point) is 100 degrees C.
heat Q
energy transfer due to a difference of temperature
Heat capacity
the energy needed to change the temperature of an object by 1 K
Heat exchanger
- A steel vessel containing pipes
- through which hot coolant in a sealed circuit is pumped, 3. causing water passing through the steel vessel in separate pipes
- to turn to steam which is used to drive turbines.
Internal energy, U
The sum of the random distribution of the kinetic and potential energies of an object’s molecules.
Latent heat of fusion
the energy needed to change the state of a solid to a liquid without change of temperature
Latent heat of vaporisation
The energy needed to change the state of liquid to a vapour without change of temperature.
Specific heat capacity, c
- SHC of a substance is the energy needed to raise the temperature of 1 kg of the substance, by 1 K, without change of state.
- To raise the temperature of mass m of a substance from T1 to T2, the energy needed Q = mc (T2 - T1), where c is the specific heat capacity of the substance.
Specific latent heat of fusion
SLHF of a substance is the energy needed to change the state of unit mass of a solid to a liquid without change of temperature.
Specific latent heat of vaporisation
SHLV for a substance is
- the energy needed
- to change the state of unit mass of a liquid to a vapour
- without change of temperature.
- To change the state of mass m of a substance without change of temperature,
- the energy needed Q = ml, where l is the specific latent heat of fusion or vaporisation of the substance.
Sublimation
The change of state when a solid changes to a vapour directly
Temperature
The degree of hotness of an object
Thermal energy
The internal energy of an object due to temperature
Thermal equilibrium
When no overall heat transfer occurs between two objects at the same temperature
