Despite this level of concentration, most trickers aren’t thinking about their work in terms of physics. A combination of athleticism and phenomenal body awareness allows these athletes to perform these feats. But behind the scenes, before and after a tricker leaves the ground, the physics of body movement is crucial to a trick’s success.
“What leads up to the jump is critical,” says John Di Bartolo, an applied physicist at New York University’s Tandon School of Engineering. “It’s just as important, or more important than the jump itself -- it’s giving them their angular momentum.”
This angular momentum is the interaction between moment of inertia and angular velocity. Moment of inertia is a quantification of how difficult it is to spin an object, a factor dictated by shape. Trickers can alter their moment of inertia by changing the shape of their bodies, throwing out legs and arms to slow down a spin at the opportune moment. The actual movement of a trick is determined by the speed and direction of motion, called angular velocity. Combined, these properties control how high trickers go, how long they’re in the air, and how fast they spin.
“What the athletes actually have control over is the rotational motion,” says Di Bartolo. These same principles of rotation are also at work in figure skating and gymnastics, but those sports only have rotation that is head over foot or spinning around the spine. Tricking is unusual because it allows for rotation around any axis a tricker can imagine, and the axis of rotation can change mid-trick. Shifting the axis of rotation through non-symmetric movement, like throwing up a single arm instead of both arms, gives tricking its unique style.
“I know the principles as far as my own mind and my body and how I apply them to tricking,” Brown says, “I just don’t necessarily know the technical terms.” But Brown uses physics to help talk about how to perform a trick, even if he doesn’t realize it. He just talks in terms of body motion and awareness, not mathematics. Understanding how to move your body to take advantage of the physics of rotation is a trick onto itself. “I think that tricking could definitely be part of something like the X Games,” says Brown. “There is that level of danger, and I feel like there is that level of skill.”
Dyani Sabin is a freelance science writer from small-town Ohio transplanted to New York City. Former crayfish chaser and library supervisor, she thinks Squirrel Girl is the greatest superhero of all time.