Kevin Coffy article (FL)

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http://www.bocaratonnews.com/index.php? ... rts%20News

A matter of physics

Published Friday, May 5, 2006
by Hannon Deutsch

Thanks in large part to an honors physics class Kevin Coffy is taking at Boca Raton High School, he understands the mathematics behind converting kinetic energy into potential energy.
Because Coffy has only been competing for three months, he relies on a basic equation in order to get optimal performance out of each vault. More often that not, the difference between clearing a specific height and knocking down the bar is so fractional.

When Coffy sprints down the 88-foot runway looking to clear an opening height of 12 feet, 6 inches at Friday's Class 3A state meet, a multitude of variables will need to be linked together into one fluid motion.

"I went into it blind," Coffy said. "I didn't understand the physics of it at first. Eventually, I would get it and go to the next step."

The strength-to-weight ratio of today's poles compensates for any wasted energy, which is the main enemy of any pole-vaulter, albeit Coffy or Ukraine's Sergey Bubka, the men's world record holder.

During his approach to the box, Coffy's kinetic energy will increase with his speed. As he plants his foot and the pole hits the box, the kinetic energy he carries transfers to potential energy. The composite materials in the pole absorb the kinetic energy through elastic deformation. Think of a spring compressing then recoiling as the stored energy is exerted. The second phase is all about angles, and any mishap can affect clearance.

"He's understood all those things," coach Harry Hackett said. "The higher speeds bring the higher grip. Then you have to fine-tune the technical parts to get the height."

A maximum of three misses per height are allowed at states. Coffy will use either a 14-foot, 170-pound pole or a 14-6, 160-pound pole. Only a sophomore, Coffy is the ninth state qualifier in the last eight years at Boca High.

His progression over the last three months has been somewhat remarkable. In February, he didn't clear anything over 8 feet. Fast forward to regionals last week. After recording a personal best of 12 feet, Coffy finished second behind Eric Foran (St. Thomas Aquinas) at 13-0.

Foran, who managed to clear 15-5 earlier in the season, is one of the favorites of the 17 pole-vaulters eyeing the 3A title at Showalter Field (Winter Park High School). Coffy is keeping his expectations in check, saying he will be satisfied with anything in the top four.

A member of the Science Technology Engineering Math (STEM) program, Coffy is getting practical use out of classroom lectures. Even if he doesn't meet his goal on Friday, the foundation has already been set for a successful high school pole-vaulting career.

"I ask questions so I'm more confident in what I'm doing," he said. "You have to predict changes."