 So here we have the equation for work non-conservative. Again, just a quick reminder, conceptually, non-conservative work is work done by any force which is not conservative. And it results in a change in the mechanical energy. Now our quick look at this equation, and we'll expand it out a little bit here, is this equation right here. W sub NC equals delta E, and the WNC is going to be the work non-conservative. The delta again means change in, and the capital E is used for mechanical energy. Again, in some books you might have a subscript here to specify that that's mechanical energy. When I look at that work non-conservative side of the equation, I need to make sure I include all sources of non-conservative work, but that I don't include any conservative work. So I could think about it as figuring out, okay, what's my non-conservative work number one? What's my non-conservative work number two? What's my non-conservative work number three? And some of these may be positive, but some of these may be negative. And once I've included everything that's non-conservative, that total is my work non-conservative. Now coming back to my equation then, I've got that total work non-conservative over here on the left side, and I've got my change in mechanical energy on the right side. But remember that change in mechanical energy could also be written out as the energy final minus the energy initial. And of course all of these terms, both work and energy terms, are going to have units of joules. So that's your quick introduction to the non-conservative equation for work.