Navier–Stokes equations

The Navier–Stokes equations are a set of equations that help us figure out what happens when fluids move. A fluid is something like a liquid or a gas. The equations tell us how a fluid will move when it is pushed or pulled around. This helps us understand the weather and why airplanes fly. The equations have been around since the 1800s and people are still trying to figure out what all the equations mean!