Thermal Physics Flashcards
What is Internal Energy
The sum of Ek and Ep of the molecules in a system
What can we say about internal energy for a monatomic gas?
As there are no forces between molecules, there is no potential energy. So the internal energy is purely kinetic.
State the equations associated with internal energy
U=3/2 nRT and U=3/2 NkT
What is absolute zero
Absolute zero is the temperature where the internal
energy of a system is at a minimum.
State the direction of flow for heat
Heat always flows from hot to cold
How does heat energy flow
Heat energy flows by conduction, convection and by radiation. This only applies for energy in transit and not for energy contained within a system
What is thermal equilibrium?
The temperature is the same on both sides of the boundary and there is no heat flow between them
Energy can also be transferred by doing what to a system?
Work
State the equation for work done by a gas
W=pΔv
Δv=change in volume
p= constantpressure
How would you calculate work done for a pressure-volume graph?
Area under the graph
Give the equation for the first law of thermodynamics at constant pressure
Q=ΔU + pΔV
If a pressure-volume graph has a curved line, what kind of work is this
Isothermal change
What does isothermal changes mean
When work is done over a long period of time
What does the first law of thermodynamics state?
The heat given to a system= increase in internal energy+ Work done by the system
Give the equation for the first law of thermodynamics at constant volume
W=0
Q=ΔU
