Question

The equation which results in the change in pressure with change in the vertical height is called as __________

(a) energy equation

(b) momentum equation

(c) continuity equation

(d) hydrostatic equation

This question was posed to me in an interview.

This interesting question is from Continuity Equation topic in division Aerodynamics – Fundamental Principles and Equations of Aerodynamics

Answer 1

The correct choice is (d) hydrostatic equation

Best explanation: dp = -g ρ dy represents the hydrostatic equation where p is pressure acting on a body, g is acceleration due to gravity, dy is changed in vertical height. The net force on the element acts only in the vertical direction. The pressure force on the front and back faces are equal and opposite and hence cancel.