Thermal physics Flashcards
Define internal energy
The sum of the potential and kinetic energy of the molecules or atoms
What are the two components of internal energy
Kinetic and Potential energy
What are the three components of kinetic energy
Translational motion
Rotational motion
Vibrational motion
What causes Potential energy
Intermolecular forces
When energy is transferred to or from a system it can take two forms, what are they.
Heat
Work
Also it is impossible to tell which form it took.
Define Heat energy
The energy which flows by conduction, convection or radiation from one body to another due to the temperature not being in equilibrium.
Flow Heat, Q is …
the energy in transit and not contained within the system
Heat will always flow from the body in … temperatures to the body in … temperatures.
Until both bodies are in …
Higher
Lower
Equilibrium
Define Work
Work is the energy that is transferred from one system to another by a force moving its point of applications in its own direction.
If heat is introduced to a gas where the set-up is such that the pressure remains constant, what will happen to the gas?
The gas will do work
What is the work done always equal to in indicator diagrams
the area under the p-V graph (indicator diagram)
What is the first law of equilibrium in words
Heat given to a system = increase in internal energy of the system + work done by the system
What is the equation related to the first law of equilibrium
Q = ΔU + W
If Q is positive Heat is …… the gas
Supplied to
If Q is negative Heat is …… the gas
Transferred from
If W is positive … work is …… the gas (…)
External
Done by
Expanding
If W is negative work is …… the gas (…)
Done on
Compressing
If ΔU is positive the internal energy …
Increases
If ΔU is negative the internal energy …
Decreases
If ΔV = 0 then W = …
0
What is the equation for Q when pressure is constant
Q = ΔU +pΔV
What is the equation for Q when temperature is constant
Q = W, since if the process is completed very slowly, any decrease in temperature will cause the heat to flow into maintain thermal equilibrium.
What is the equation for Q when the volume is constant
Q = ΔU, since ΔV = 0 so W = 0
What is the equation for ΔU when there is no heat flow, Q = 0
ΔU = - W
What is the equation for Q for liquids and solids
Q = ΔU, since volume barely changes.
What is the equation for specific heat capacity
Q = mcΔθ
Define Specific Heat capacity
The heat required, per kilogram per degree kelvin to raise the temperature of a substance
Describe Absolute Zero in terms of internal energy
It is the temperature of a system when it has minimum internal energy