Question

I have a question regarding to Clausius Theorem and Inequality and Second Law of thermodynamics.
The Clausius Theorem and Inequality: ds=dQ/T
The Second Law of thermodynamics: ds=Q/T
Why these two are different? It's confuse me a lots.
Thanks.

Answer 1

I'm not sure if there is a huge difference mathematically. The only part I can see is that the condition for Clausius states that the integral of the change of entropy must be equal to 0 or is negative, whereas the 2nd Law provides the general fundamental relationship of S, Q, and T. Clausius would be an extension of the 2nd Law, I'd imagine.

I haven't taken heat transfer nor thermodynamics yet, but that's what I seem to gather from HyperPhysics:

`Clausius Theorem & Inequality:` http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/clausius.html
`2nd Law of Thermodynamics:` http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/seclaw.html