When Bears linebacker Brian Urlacher slams into a running back during Sunday's Super Bowl, he'll experience a force of 10 G's – more acceleration than astronauts feel during a rough landing. When two players collide helmet to helmet, the force can be the equivalent of getting conked on the head by a 16-pound bowling ball dropped from a height of 12 feet. And when a receiver catches a "bullet pass," it's the equivalent of stopping four actual bullets fired from a .44 Magnum.
Those are just a few of the science facts you can snack on during the big game, courtesy of University of Nebraska physicist Tim Gay, former football player and the author of "Football Physics: The Science of the Game." Gay has a knack for making the gridiron game sound a lot more painful than it looks.
"Football, after all, is a contact sport," he told me today. "When you watch the game, and Urlacher puts a hit on [Colts running back Joseph] Addai, those are big forces. Those forces approach that of a ton. That's all the result of Newton's laws of mechanics and motion."
How can the crash of two big men possibly summon up the power of 2,000 pounds? And if that's really the case, how can they survive that kind of blow? "It's because of the sharpness of the blow, the fact that it only occurs for a tenth of a second," Gay answered. "Because this is such a short, sharp hit, you can survive it."
That's the trick behind a lot of the forces involved in full-contact football. Gay cited another example, relating to running backs.
"It's always impressive to realize that when they make a sharp cut to avoid a defender, they're putting about 800 pounds of force through their ankles," he said. "If someone experienced that force for about 10 seconds, he'd be moving at the speed of jet aircraft. Those kinds of big forces are what make the game exciting for me."
Gay even played the game himself, as an offensive tackle for the Caltech Fighting Beavers. He went on to do research in atomic physics, but his connection to Cornhusker football is what really brought him into the public eye.
Over the years, Gay has explained the physics of the sport to football fans on Husker Stadium's big screen during breaks in the action - and he's also explained American football to the rest of the world in a series of commentaries for ESPN's international outlets. You can still find a selection of Gay's one-minute football science lessons online - and they're hilarious.
All that air time has given Gay plenty to talk about. For example:
Because the football is a "prolate spheroid" - that is, an elongated object that's built to spin around its long axis - it behaves like a gyroscope. But that doesn't mean it goes in a straight line from point A (quarterback) to point B (receiver). "Because the ball is spinning, the aerodynamic drag causes it not to tumble end over end, but it will veer to the right or the left," Gay said. A ball thrown by a right-hander - such as the Colts' Peyton Manning or the Bears' Rex Grossman - will veer slightly to the right.
The truism that real grass slows down a fast football team is really true, according to at least one published study. The reason? Runners expend some of their energy sinking down into natural turf, while all that energy can go into lateral movement on artificial turf. "The problem is that it doesn't actually lead to any fewer yards per carry, and the reason for that is that it slows down the defense, too," Gay said.
There's a reason why the penalty is so severe for grabbing an opponent's face mask and twisting it around: "If someone grabs your face mask, it's the equivalent of sticking your head in an industrial washing machine, because there's so much torque," Gay explained.
Finally, consider how much energy football players expend on the field, compared to how much you expend watching them. "If you're sitting around watching the Super Bowl, eating nachos, your body expends about a seventh of a horsepower," Gay said. He said athletes (for example, bicyclist Lance Armstrong) are capable of sustaining about three-quarters of a horsepower continuously for a couple of hours. But football tackles can work themselves up to the level of 5 hp - for a few seconds, that is.
Based on his scientific analysis, how does Gay think the Super Bowl will turn out? He didn't come right out and make a prediction, but he did say he was looking forward to the action as well as the equal and opposite reaction.
"This will be an excellent game," he said. "Manning is a great passer."