Question

Suppose you have a fluid that is NOT incompressible, like air. As you go up in the Earth’s atmosphere the air pressure drops and so does the air density. Can we use the equation p = p0 + ρgh to calculate air pressure with depth in the atmosphere? Explain why or why not.

Answer 1

Here you are above surface of water, and that equation is valid only underwater.
p = p0 + rho * g * h. since we are above water h = 0, and p0 is getting smaller since air pressure drops