Education Law

Olympic science

BoardBuzz has been enjoying the Games of 29th Olympiad, but it got us thinking. How do our world's athletes continue to improve and break records every four years? Moreover, what's the science behind such impressive athletic performances? Well, we've done some delving into that very topic, and now it's time to share.

Today we're going to look at the pole vault. Pole vaulting is a track and field event in which an athlete jumps over an obstacle with the aid of a pole. Originally a practical means of clearing obstructions, such as ditches, canals, and fences, pole-vaulting for height became a competitive sport in colleges during the mid 19th century. In the 1896 Olympics, the record, set with a bamboo pole, was 10 ft 6 in (about 3.2 m).

There are several phases to the pole vault event which include the approach, the plant and take off, the swing and row, the extension, the turn, and the fly-away. Britannica describes the event thusly:

Requirements of the athlete include a high degree of coordination, timing, speed, and gymnastic ability. The modern vaulter makes a run of 40 metres (131.2 feet) while carrying the pole and approaches the takeoff with great speed. As the stride before the spring is completed, the vaulter performs the shift, which consists in advancing the pole toward the slideway and at the same time allowing the lower hand to slip up the pole until it reaches the upper hand, then raising both hands as high above the head as possible before leaving the ground. The vaulter is thus able to exert the full pulling power of both arms to raise the body and help swing up the legs.

The vaulter plants the pole firmly in the box, and, running off the ground (rather than jumping), the vaulter?s body is left hanging by the hands as long as possible; the quick, catapulting action of the glass-fibre pole makes timing especially important. The legs swing upward and to the side of the pole, and then shoot high above the crossbar. The body twists to face downward. The vaulter?s body travels across the crossbar by ?carry??the forward speed acquired from the run.

However, the key point is the interaction between vaulter and pole. The vaulting pole is both a remarkably simple yet advanced piece of equipment. Constructed from layered carbon fiber and fiberglass composites, the pole must absorb all of the vaulter's energy while bending after the plant, and then return all of that energy as it straightens out.

So what does the science say? The pole vault is all about energy conversion. Kinetic energy is built up during the approach run which then turns into potential energy stored in the pole as the vaulter bends it nearly 90 degrees. When the pole recoils, it unleashes that energy to help propel the vaulter up and over the bar. The physics expression looks something like this if you assume a complete kinetic to potential conversion: ½(v² / g) = h.

However, this expression needs to be adjusted slightly to account for the vaulter's height. The adjustment has to do with the vaulter's "center of mass," a specific point at which a body's mass behaves as if it were concentrated. For people, the center of mass is roughly half their height. So now we have: h= 0.5 * [your height] + ½(v²/g). Enter in the approach velocity in meters/second and the athlete's height in meters and you get a good estimate of their vault height. Oh, and gravity (g) is 9.8m/sec².

It's all physics. Physics and some impressive athleticism.

Full post as published by BoardBuzz: NSBA's Daily Weblog on August 12, 2008 (boomark / email).