Final answer:
Bernoulli's Equation is used to determine the mass flow rate out of an opening under fire conditions, applying conservation of energy and the continuity equation principles.
Step-by-step explanation:
The formula used to determine the mass flow rate out of an opening under fire conditions is Bernoulli's Equation. This equation describes the conservation of energy in a fluid flow and can be applied to the situation of fire conditions to determine the mass flow rate. The continuity equation, which is based on the conservation of mass, states that the mass flow rate entering a volume is equal to the mass flow rate leaving the volume. When considering an incompressible fluid in a pipe that has a varying diameter, Bernoulli's Equation helps us understand the relationship between pressure and velocity, contributing to the calculation of mass flow rate.