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If you’ve ever tried to throw a spiral, you know it is not easy. Good quarterbacks use a flipping motion that puts a spin on the ball. Footballs thrown without the spiral don’t travel any significant distance. The forces of gravity and air drag are just too strong. Do spiral throws go higher? Or farther? No, they don’t, even though most people think they do. Let’s look at the physics.

The spiral pattern minimizes the forces of gravity and drag that are working to bring a thrown ball down to earth.

Think of a physics experiment where you have a spring-loaded ball launcher. The launcher would allow you to launch the ball—not spinning—into the air at a particular height. If you modified the launcher to make the ball spin, would the ball go higher? Actually, the spinning ball will not go as high. The spin requires some of the energy of the ball’s motion. When that energy is taken up by the spin, it is not available for motion, so spinning balls reach lower heights than non-spinning balls. As soon as the quarterback throws the ball, the total energy is set as the ball starts in motion. That energy can’t change, but it can take different forms. When a football is thrown, there is linear kinetic energy, meaning how far down the field or how high the ball travels

14 CONNECTING STEM AND SPORTS | FOOTBALL