# 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

 $$\large{ A_1 \; v_1 = A_2 \; v_2 }$$

### Where:

$$\large{ A_2 }$$ = final area cross-section

$$\large{ A_1 }$$ = initial area cross-section

### $$\large{ v_2 }$$ = final cross-section velocity

$$\large{ v_1 }$$ = initial cross-section velocity