Clemson professor Amy Pope sees sports as a lesson in the principles of physics
When Amy Pope, principal lecturer in physics and astronomy at Clemson University, attended a football game a few years ago, she had a revelation.
It wasn’t that she suddenly became a supporter of the Tigers, having already earned her B.A., M.S., and Ph.D. degrees in physics at Clemson. Instead, the team showed her a new way to approach the subject she had spent so many years studying and teaching.
“I traveled with the athletes the night before, and I was sitting in the meeting before the game when they were discussing strategy,” she says. “I understood every single word they said, but contextually, when they put all the words together, I had no idea what the strategy for the game was.”
That’s when the revelation occurred. “I realized that that’s what some students must think about physics when they look at it,” she says. “So that’s why I decided to look at the sports.” When she began illustrating the principles of physics with sports, her students could grasp them more easily, she found.
Principles of Physics
All sports demonstrate Newton’s laws of motion to some degree, says Pope, but when it comes to one pastime popular during summer in the Southeast, there’s one particular force she sees at work.
“When you talk about golf, it’s all about rotation, particularly rotation relative to the ground,” she says.
A golfer swinging a club is similar to the torque of a wrench tightening a bolt, says Pope, as the wrench provides a lever to put a rotational force far away from the axis of rotation (the bolt). To get the necessary torque, a golfer must maintain a stable axis of rotation—with the help of the right pair of shoes.
“You have to have those spikes on the shoes,” she says. “The spikes on golf shoes are twisted to help the golfer stay firmly planted in the ground as the whole body twists around.”
Newton’s third law, describing action and reaction, comes into play once the club connects with the ball and potential energy is converted to kinetic energy—something else that golfing equipment has evolved to maximize.
“The clubs were first made of wood, and there was a lot of energy loss,” Pope says. “Most modern clubs are made of titanium, and that is huge, because that lighter titanium is going to allow us to conserve more energy.”
Here, the metric is the coefficient of restitution (COR), measuring how much energy is transferred from the club to the ball. COR values range between zero (no transfer at all) to 1 (perfect transfer). As club manufacturers got better at pushing the number up toward 1, the United States Golf Association set the maximum COR limit for 0.83 for drivers.
“That kind of evens the playing field,” Pope explains. “As long as you have a nice golf club, if that ball enters the impact at 100 miles per hour, it will exit at 83 miles per hour.” Whether they realize it or not, golfers are also dealing with the physical force of angular momentum, essential in maximizing speed and distance.
In the classroom, Pope has used data gathered during the Clemson golf team’s use of the Trackman simulator to give a new perspective on the laws of physics. Her students don’t stop there, exploring the forces at work in activities such as football, baseball, boxing, and even Olympic breakdancing.
And, Pope notes, they might soon find one more sport on the curriculum.
“I’ve been looking at curling,” she says.
Improve Your Game with Sweet Spot Science
In golf and all other projectile-whacking sports, players are always looking for the “sweet spot.” But what’s the science that makes that spot so sweet?
In physics terms, the sweet spot, aka, the center of percussion (COP), is the place at which an object being struck will absorb the maximum forward momentum of the object striking it. Hitting a golf ball away from the sweet spot creates twisting of the head, along with vibrations that travel up the club to the grip—releasing energy that could have been applied to the ball. The result is a shot that loses velocity and goes wide.
A club head’s POC is usually in the center, although it can vary from club to club depending on design. Many pros can pinpoint the POC within millimeters. The scientific method can help if you apply impact tape or foot powder to the head to show exactly where it’s impacting the ball. Once you’ve landed the sweetest shot, you’ll know you’ve found the sweet spot.
