First Law of Thermodynamics

Where is the VdP part of the equation?

Should VdP also be negative so that the differential equation can be integrated? (into W=-PV)

What if you had a pressure change but not a volume change?

I'm pissed because you are all stating this like it's such common sense. Even your last post only uses simple algebra. I already know these backbone equations. I want to know why they work conceptually. So far, Stereo is the only person who tried to, but he didn't follow through and explain the rest:

Thank you to be the first one for trying to explain. However, I still don't understand why pressure can't change in from an external force. Why must it be entirely from an internal force? Suppose that there's a random mass of gas in space and there's entirely nothing around. (Okay, that's not entirely true because there's always gravity, but let's just assume that the gravity is negligible or 0.) Then there can only be outward expansion because the molecules that are moving must collide into each other and bounce off of each other and travel towards nothingness.

Then the volume increases and the pressure decreases, and where's the work done? Also, if dW is already work done, what does integrating it and getting W give you?

I posted this topic in the Speakeasy and the Rubik's Cube because I assumed that some of you must have taken at least one class that explains these concepts, and if you have, that these questions should be fairly easy to explain (and therefore not "intelligent discussion"). And what do I see? Some dude's marching band that apparently needs "intelligent discussion", and my topic being treated like it's crap from the Funhouse.

Links to wikipedia articles. Having the equations typed out in words. Wow.