Aerodynamics
Aerodynamics is the study of how air moves around objects and pushes on them.
Hold a flat tray level in the air, then tilt it. Air hits the raised front edge and pushes the tray up or down. A curved tray, higher in the middle, splits air so it moves faster over the top. Faster air pushes less from above, so the tray lifts.
Explaining aerodynamics by grade level
Wind pushes on things. A flat wall catches more wind than a round pole. Think about a tall building in a storm. A round building lets wind slide past, but a flat one gets pushed hard. Shape changes how much the wind can push.
Projects that explore aerodynamics
A flat surface acts like a sail — and a fully covered bridge wall proves it. When you place three toothpick-and-string bridges one meter from an industrial fan, the open-sided bridge tilts only 3 degrees. The fully covered version, with paper walls catching the crosswind directly, tilts 37 degrees. More side coverage means more wind catches the structure and pushes harder on it.
Shape determines how air flows around a structure and how much force it absorbs. When you mount four polystyrene models — rectangular, triangular, circular, and oval — inside a plywood wind tunnel and gradually increase fan speed, the rectangular model topples first. Its flat face meets the air head-on, concentrating force directly against it. The circular model withstands the highest wind speed before collapsing, because air moves smoothly around its curved surface and spreads that force instead of focusing it in one place.