I'm not sure if this should go in this section or the homework section but I'm having a problem fully understanding what a derivative means in a real world application. My class started moving into basic application problems but I'm not sure what the derivative means. An example of what I mean is a ladder problem in my cal book. A ladder at 90 degress is sliding horizontally at 2 ft/sec, and in the solution section it says that dx /dt = 2 ft/sec is a given but I don't know why that is a given. In the other example problems any numbers that are "going at a rate of" the solution in the text is saying that that number is the derivative with respect to time, but I don't understand why and can't conceptually understand what that means The way I understood derivative is that it is the slope of tangent line. So if anyone could explain this to me I'd really appreciate it.