Physics__Thermodynamics Flashcards
What is internal energy?
The sum of the kinetic and potential energies of all the molecules within a given mass of a substance
What’s specific heat capacity?
the energy required to raise the temperature of one kilogram of a substance by one kelvin
What is latent heat?
The thermal energy required to change the state of one kilogram of a substance without any change of temperature
What are the two types of latent heat?
Specific latent heat of fusion (melting)
Specific latent heat of vaporisation (boiling)
What’s the specific latent heat of fusion?
The thermal energy required to convert one kilogram of solid to liquid with no change in temperature
Whats the specific latent heat of vaporisation
The thermal energy required to convert one kilogram of liquid to gas with no change in temperature
What is absolute zero?
The temperature at which the molecules in a substance have zero kinetic energy
Equal to 0 K or -273.15°C
What are the assumptions of kinetic theory
A gas consists of a very large number of molecules (Evidence: Brownian motion).
These molecules are in continuous, rapid, random motion.
Collisions between molecules, and between molecules and the walls of a container are perfectly elastic (Evidence: Brownian motion, gas temp. constant).
The volume occupied by the molecules themselves is negligible compared with the volume of the container. (Evidence: easy to highly compress gas)
Intermolecular forces are negligible except during a collision. (Molecules are v. far apart compared with their size so intermolecular forces become v. small)
The duration of collisions is negligible compared with time spent in between collisions (Evidence: molecules are v. far apart compared with their size)
What equation should be used for an ideal gas?
pV = NkT
N is the number of molecules
k is the Boltzmann Constant
T is temperature (K)
V is volume (m3)
P is pressure (Pa)
What is black body radiation? And what is a perfect black body?
The thermal radiation emitted by all bodies (objects)
A perfect black body: An object that absorbs all of the radiation incident on it and does not reflect or transmit any radiation
Whats thermal equilibrium?
When a system remains at constant temperature, as it is radiating energy at the same rate as its absorbing energy
Whats Boyles law?
The pressure of a fixed mass is inversely proportional to its volume, provided that the temperature is kept constant
