Me: The air flow in the duct is steady and uniform across the duct cross section, If the convective acceleration at a is -2m/s^2, what is the pressure gradient dp/dx at that point? The density of air is 1.2kg/m^3. The duct is in a shape of a diffuser and the required point is at a distance of 0.5m from its entrance Solution dp/dx=-density x aceeleration =-1.2x(-2)=2.4 N/m^3 .