# Continuity Equation for Mass

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

This formula states that the mass entering a system is equal to the mass leaves the system both at the same rate.

## Continuity Equation for Mass formula

$$\large{ A_1 \; v_1 = A_2 \; v_2 }$$
Symbol English Metric
$$\large{ A_2 }$$ = final area cross-section $$\large{in^2}$$ $$\large{mm^2}$$
$$\large{ A_1 }$$ = initial area cross-section $$\large{in^2}$$ $$\large{mm^2}$$
$$\large{ v_2 }$$ = final cross-section velocity $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$
$$\large{ v_1 }$$ = initial cross-section velocity $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$