thermodynamics coordinate


by renhoran
Tags: coordinate, thermodynamics
renhoran
renhoran is offline
#1
Feb28-13, 01:07 PM
P: 1
i don't really understand which quantities are thermodinamic coordinates and which are not. and what makes work and heat are not thermodinamic coordinates but temperature, volume, etc are thermodinamic coordinates?
Phys.Org News Partner Physics news on Phys.org
Physicists consider implications of recent revelations about the universe's first light
Vacuum ultraviolet lamp of the future created in Japan
Grasp of SQUIDs dynamics facilitates eavesdropping
rock.freak667
rock.freak667 is offline
#2
Feb28-13, 06:24 PM
HW Helper
P: 6,214
What do you mean by "thermodynamic coordinates"? If you mean those P-V, T-S, P-H diagrams and such then work and heat are as a result of the changes in pressure, temperature, enthalpy and so on.

So it makes more sense to plot state changes rather than the work done in the process.
Philip Wood
Philip Wood is offline
#3
Mar1-13, 11:37 AM
P: 863
Take the simple example of a sample of gas with a fixed number of molecules. It need not be ideal. Its temperature, T, can be expressed as a function of just two variables, volume, V, and pressure, p. We can, it turns out, express all gas properties as functions of just two variables (such as p and V or p and T). These properties include refractive index, viscosity, internal energy, entropy, enthalpy, the Helmholtz function, the Gibbs function. We call these properties 'functions of state'. The state is determined by the values of just two variables.

Heat and work are not functions of state. They are not properties of the gas. They both represent energy in transit to or from the system, not energy residing in the system.


Register to reply

Related Discussions
Converting global coordinate data to local coordinate in MATLAB General Engineering 0
Convert this rectangular coordinate system point to spherical coordinate system Calculus & Beyond Homework 1
coordinate singularities and coordinate transformations Special & General Relativity 7
How to convert cylindrical coordinate to cartesian coordinate? Precalculus Mathematics Homework 1
Coordinate transformation and choice of a suitable coordinate system. Special & General Relativity 2