Question

Prairie dogs ventilate their burrows by building a mound around one entrance, which is open to a stream of air when wind blows from any direction. A second entrance at ground level is open to almost stagnant air. How does this construction create airflow through the burrow?

Short answer

A breeze from any direction speeds up to go over the mound and the air pressure drops. Air then flows through the burrow from the lower entrance to the upper entrance.

Step-by-step solution

Pascal’s law

The pressure in a fluid at rest varies with depth h in the fluid according to the expression:

$P=P_0+\rho gh$

Where $P_0$is the pressure at $h=5$and $\rho$is the density of the fluid, assumed uniform. Pascal’s law states that when pressure is applied to an enclosed fluid, the pressure is transmitted undiminished to every point in the fluid and to every point on the walls of the container.

Explain the reasoning

A breeze from any direction speeds up to go over the mound and the air pressure drops. Air then flows through the burrow from the lower entrance to the upper entrance.