It’s Super Bowl LVII time, and this year the Philadelphia Eagles are squaring off against the Kansas City Chiefs for the championship title. While the Chiefs are returning for their third final in four years, bets are slightly favored towards the Eagles as they’ve kept a strong and consistent offensive line all season, led by quarterback Jalen Hurts. But the Chiefs could defy the odds if quarterback Patrick Mahomes fully recovers from an ankle sprain he sustained more than a week ago against the Cincinnati Bengals.
[Related: We calculated how much sweat will come out of the Super Bowl]
Ultimately, the game could come down to every single throw. Mahomes has already proven he can hit his mark in most circumstances: His football spirals are the “closest we’ll see to breaking the law of physics,” says Chad Orzel, an associate professor of physics and astronomy at Union College in New York. “He manages to make some amazing passes from bizarre positions that wouldn’t look like they would produce anything good.” Hurts has also been leveled up his game this season through “meteoric improvements” in his throws.
Throwing the perfect football spiral might seem like something reserved for Super Bowl quarterbacks. But with some practice and science know-how, you too can chuck up the perfect spiral.
Why do football players throw spirals?
Unlike baseball or basketball, the American football relies on a spiral rotation because of its prolate spheroid shape. If you make the ball spin fast enough, it will stay in the same axis it’s pointing towards and hit the intended target straight-on, Orzel says. This follows the conservation of angular momentum: an object preserves its rotational speed if no external force is acting on it.
Think of a spinning top. When you twist the toy and release, it will rotate in the same direction that you wound it up in, and will continue to stay upright in that angle until another external force (like your hand) causes it to stop. “It’s the same idea with football,” explains Orzel. “If you get the ball spinning rapidly around its axis, it’s a little more likely to hold its orientation and fly through [the air] in an aerodynamic shape.”
[Related: Hitting a baseball is the hardest skill to pull off in sports. Here’s why.]
In a game where you have seconds to pass before you get tackled or intercepted, the biggest priority is to flick the ball with its nose pointed toward you. This confers less air resistance, meaning the ball can travel farther in a straight path (as long as it doesn’t meet outside forces like strong winds), explains John Eric Goff, a professor of physics at the University of Lynchburg in Virginia and author of Gold Medal Physics: The Science of Sports. A wobbly pass will result in more air drag and take longer to reach its destination, he adds. If you have to duck a defender and then pass the ball off quickly, you will get erratic air drag, which also hurts the accuracy of the throw.
How to throw a football spiral
To get a great spiral, you need to master angular momentum, which involves a few key physical factors. First, a person’s grip on the laces of the ball acts as torque—a measure of force applied to an object to rotate on its axis. In other words, the friction from the fingers gives the ball traction to spin.
Second, you need to perfectly balance the frictional force on the ball and the forward force needed to give the ball velocity. This requires strong core muscles to rotate the body all the way through the shoulder and increase throwing power. “Tom Brady used to practice drills where he would rotate his torso quickly to help develop fast-twitching muscles in his core,” says Goff.
Third, the hand must also be on the back of the ball to give it forward velocity, but not too far back to prevent the necessary torque for the spin. “A typical NFL spiral rotates at around 600 rotations per minute, which is the low end of a washing machine’s rotational rate and about 30 percent greater rotation rate than that of a helicopter’s rotor blades,” adds Goff. “Pass speeds are typically in the range 45 to 60 mph—the same range for cars entering and driving on highways.” For maximum force, pull the ball back to your ear just above your armpit, then release it with your elbow fully extended. Your wrist should point down at the end of the pass.
Knowing the physics behind a football spiral is only half of the battle. Both physicists emphasize the importance of practice. Practice can be as simple as watching videos of pro footballers, studying their technique using computer simulations, and playing a game of catch at the park with friends.
Achieving a perfect spiral is challenging but doable. Even your favorite NFL quarterback might have started with a clumsy first toss. But with practice, they’ve become the ideal throwing machines we cheer for every year.