Hello! I have just rediscovered this place since a few years back when I first signed up. This will be my first post, so forgive me if it is a bit long. I have been thinking about this for a while. So I have been thinking about buoyancy. I have learned that the buoyancy force is caused by a change in pressure per change in depth, and that for incompressible fluids, the buoyancy force remains constant at any depth. So this got me thinking about compressible fluids and that the buoyancy force changes at different depths. My first question is does the change in pressure per depth increase or decrease as you go deeper in a compressible fluid? Then this got me thinking about different situations, like can I tell at what depth an object is neutrally buoyant in a compressible fluid? My mind then started to draw parallels from buoyancy force in compressible liquids to air drag force, because air drag force is changing as an object's falling velocity increases. Then I started to think about how I could derive at what falling distance does it take for an object to reach terminal velocity. This stuff is all interesting to me now, but I've never been able to put any of the math I learned to good use. No one really showed me how to derive things, especially when dealing with changing rates. Is it too late to ask?