1.8 Thermal physics Flashcards
What is a thermodynamic system?
The collection of particles within a volume of space
Define isolated system
A system which does not allow energy or matter to enter or leave
Define closed system
A system from which matter cannot enter or leave (an isolated system is also closed)
Define heat engine
A system which converts thermal energy into mechanical work
Define internal energy
The internal energy of a system is the sum of the potential and kinetic energies of its particles
Define heat
Heat, Q, is the spontaneous flow of energy in response to a difference in temperature. It flows from a high temperature to a low temperature
Define temperature
Temperature is defined as the direction of heat flow, heat will flow from an object of higher temperature to an object of lower temperature. If there is no heat flow between two objects, they are the same temperature
Define thermal equilibrium
If two systems that are in thermal contact have no heat flow between them, then they are in thermal equilibrium. This means they are also at the same temperature
What is the zeroth law of thermodynamics?
Two systems which are separately in thermal equilibrium with a third system will be in thermal equilibrium with each other
How does work done link to pressure and volume?
W = p(delta)V, as long as the pressure remains constant. This is also given by W = the area under a p-V graph
What is the first law of thermodynamics?
When net heat, Q, flows into a system which does net work, W, on its surroundings, the internal energy U changes according to the relationship (delta)U = Q - W
Define specific heat capacity
The specific heat capacity c of a material is given by Q = mc(delta)(theta), where Q is the heat input, m is the mass, and (delta)(theta) is the temperature change. This can be described as the heat per unit mass needed to raise the temperature of a material by 1 degree
