UNL physicist breaks down the science behind the perfect throw

UNL physicist Dr. Timothy Gay explains the science behind what happens when a football is thrown, and how to potentially improve those long passes.
Football Pic

LINCOLN, Neb. (KLKN) – Husker fans are gearing up for Saturday’s season opener against Ohio State, but many of them won’t be thinking about the science behind the plays while they’re watching.

Some fans, however, will be. Dr. Timothy Gay is one of those fans.

As a physicist at UNL, Dr. Gay has studied the science behind the sport for years.

“I knew when I was in high school I wanted to be a physicist and I knew that I loved football,” Gay says.

From the amount of force that used when players make tackles, to how their equipment works, Gay has studied it all. But, there is a question that remained unsolved for him for a long time: why does the nose of the football tilt upwards when it’s thrown, but downwards when it’s caught?

“I got interested when I observed long bombs, tight spiral passes that would go up at some angle, and they would turn over. In other words, the balls axis would follow the line of trajectory,” Gay says. “As the ball is launched, its tilted up, at the top of the trajectory, the axis of the ball is horizontal, and as the receiver is about to catch it, the ball is tilted down by about the same angle it was thrown but in the opposite direction. You would expect it to go up and come down not having changed its angle, instead what it does it turn over.”

After 15 years, and a lot of help from fellow physicists, Dr. Gay and his colleagues found an answer.

“It has to do with angular momentum, but not the angular momentum of any spinning object, but like that of a gyroscope,” Gay says.

Like the enthusiastic, passionate educator he is, Dr. Gay explained the angular momentum of a football to Channel 8 Eyewitness News reporter Marlo Lundak.

Gay winds up the gyroscope, which results in it spinning like a top on the flat table.

“You will see that the tip of the gyroscope is executing a little circle at a slower rate of rotation,” Gay says. This process is called procession, and in the case of a football that has just been thrown, that’s what makes the ball stay aligned with the air molecules it’s running into.

“The ball tries to orbit around in a tight circle that incoming direction of the air.”

Overall, the tight spiral and the drag that’s provided by the air around the ball that allows it to tip forward as it’s thrown, rather than staying in the position and angle it was launched in.

As part of his research, Dr. Gay is also working on what might give players and teams an ‘extra edge,’ and how physics can help improve players’ passing game. 

“Instead of throwing so the axis of the ball is perfectly aligned with the ball’s direction, instead, to throw the ball tilted to the side just a little bit, perhaps two or three degrees.”

Dr. Gay says it wouldn’t be a major game changer, but could give a team a slight edge, a few more yards on a long pass, and the potential for more points, if it comes down to it.

Finally, based on his knowledge of football, both as a fan and as a physicist, we asked Dr. Gay who, according to physics, has the better chance of throwing a perfect ball – Martinez or McCaffrey. And while he says he hasn’t studied McCaffrey’s throw as closely as Martinez, there’s more to a player than the science.

“No player is ever going to disobey the laws of physics,” Gay says. “But there’s a whole lot more that goes into what makes a great football player. There’s talent, there’s heart, and physics doesn’t have a whole lot to say about the heart aspect of it.”

Dr. Gay recently published a book about his research, “Football Physics: The Science of the Game.”

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