As APS’ new science writing intern, I’m excited to join the Physics Buzz blog team. I’m migrating out east from the frigid Rocky Mountains where I studied physics and philosophy at the University of Colorado at Boulder. Before coming to APS, I got my feet wet writing about everything water at the American Water Works Association.
My blogger name, Hyperspace, was actually a nickname I picked up during college. I’m an avid ultimate frisbee player, and my quick feet coupled with my physics background gave rise to the name. In honor of one of my favorite pastimes, I’d like to use my first post to give you a crash course on the physics of frisbee flight.
There are two main ingredients for disc flight: lift and spin. Like on aircraft wings, air takes longer to travel across the curved top surface of the frisbee than on the bottom. Consequently, the air on the bottom exerts more pressure on the disc, keeping it aloft.
More advanced players invert the disc for “hammer” throws. When inverted, the air can’t follow the sharp leading edge of the disc’s grip as easily, causing a turbulent air pocket to form above the frisbee. When the disc loses its initial forward momentum, it plummets to the ground quickly. In the hands of an experienced thrower, this leads to quick, precise throws to the open receiver in the back of the end zone. In the hands of a novice, it can often lead to innocent bystanders being pelted with pieces of plastic.
Spin—as any ultimate player will tell you—determines the accuracy and strength of a throw. Because air usually exerts more lift on the front end of the disc, non-spinning frisbees tend to tilt upward until they flip over. To combat this aerodynamic torque, players put as much spin as possible on the disc when they throw it. Faster rotation increases angular momentum and causes the individual torques on the disc to cancel each other, leading to a flatter flight.
So next time you take your dog to the park for some disc tossing, remember that there’s a great deal of physics involved. But calculating the net forces on a frisbee while you’re throwing it might not be the best way to improve your game. Practice makes perfect.