Topic 3 - Thermal Physics Flashcards
Define heat (Q; Joules)
Transfer of energy between a system and its surroundings // The transfer of energy (thermal energy) between two substances/systems due to a temperature difference.
Define temperature (T; Kelvin (or degC))
Average kinetic energy of the molecules
Define internal energy (u; Joules)
The total energy (sum) of the kinetic and potential energy.
u = Ek + Ep (KE + PE)
What happens to the temperature as velocity of particles increases?
T measure of avg KE
Since m constant, E is prop to v^2
Thus larger velocity means higher temperature
Faster particles means hotter. The slower they go the colder it is.
Define/outline ideal gas
No forces between molecules
Must work for all pressures, volumes and gases (a nombre of assumptions/relations)
What are the assumptions of ideal gas law
No forces between particles
The gas particles have negligible volume compared to the volume of gas
Any collisions between particles are completely elastic
They move randomly in agreement w newtons laws of motion
When does the ideal gas law work well?
At rel LOW PRESSURES
and rel HIGH TEMPERATURES
Refer to change velocity and pressure vs volume ideal gas
If vol decr p incr
P = F/A
Temp = avg KE (the faster they move the hotter the gas)
What is n in ideal gas law
The NUMBER OF MOLES
Gas law Constant volume
Since v, n, R constant —-> p prop T
As temp incr so does p. Linear graph
Gas law Charles’ law pressure constant
V prop T
n R p constant ——> V prop T Linear graph posrel.
Gas law Boyle’s law T constant
T R n constant —-> pV = smth constant —-> p prop 1/V Gives NOT linear graph, 1/x (1/V)
