What happens to the velocity of air when the area of the airway is reduced?

When the area of an airway is reduced, the velocity of the air increases—a principle rooted in fluid dynamics, often referred to in the context of the continuity equation. This equation states that for a fluid flowing in a closed system, the product of the cross-sectional area (A) and the velocity (V) must remain constant. Therefore, if the area decreases, the velocity must increase to maintain the same flow rate.

In mining environments, understanding this relationship is crucial for air quality management and ventilation systems. A higher airflow velocity can affect dust control, gas dilution, and the overall safety of miners in the environment. This dynamic can also influence the rate at which contaminants are removed from the work area, impacting ventilation design and operational efficiency.

Choices that suggest the velocity remains unchanged or decreases contradict this fundamental principle of fluid mechanics, as they do not take into account the necessary adjustments to maintain constant flow when cross-sectional area is decreased. Fluctuations in velocity would imply an irregular flow pattern, which is not expected under steady-state conditions where the air is continuously moving through a confined space.