Physics | Mathematics | Science on Instagram: "A boat propeller works by pushing water backward. According to Newton’s 3rd Law (action and reaction), the water pushes the boat forward. The propeller blades have a special shape, and as they spin, they create a pressure difference that generates thrust. The faster it spins, the more force it produces. This is the basic principle of aquatic propulsion. A controllable-pitch (or variable-pitch) propeller allows the angle of the blades to be adjusted