In: Physics
derive first law of thermodynamics formula with calculus?
Note that +pdV is the work done by the system, while −pdV is the work done on the system. The preceding derivation should make clear that e is the internal energy of the fluid associated with random motions of the molecules that comprise the fluid, while the source/sink term dq is the heat added to or lost from the fluid. Consistent with kinetic theory, the internal energy e depends only on the temperature of the fluid. For example, if the fluid is at rest, it has zero macroscopic kinetic energy because the mean velocity of the molecules in the fluid is zero, but an increase in temperature of the fluid increases rms molecular speeds, thereby increasing the internal – or microscopic – energy of the fluid.