How is the quantity of air in a ventilating current determined?

The quantity of air in a ventilating current is determined by multiplying the area of the airway by the velocity of air flow in feet per minute. This relationship is grounded in the principles of fluid dynamics, specifically the continuity equation, which implies that for air to flow through a certain area, the product of the cross-sectional area and the velocity must equal the volumetric flow rate.

When you consider the area of the airway, it provides the space through which air can move. The velocity indicates how fast the air is moving through that space. By combining these two factors, you can effectively calculate the volume of air transported per unit of time, which is critical for ensuring proper ventilation in mining operations. Proper ventilation is essential for maintaining air quality and safety in mines, where the presence of harmful gases and dust can pose serious health risks.

The other options, while they may relate to air movement and pressure in some way, do not directly compute the quantity of air in a ventilating current in the way that the correct answer does. For example, measuring pressure difference can provide insights into airflow dynamics but does not quantify air volume directly. Similarly, the airflow rate and temperature are important in understanding air conditions but do not contain the specific relationship required for calculating air quantity.