Comment »Posted on Thursday 11 September 2008 at 2:43 pm by Jacob Aron
In Physics

The most impressive moment of the Beijing 2008 Olympics was when Usain ‘Lightning’ Bolt not only beat the world record for the 100 metre dash, but actually slowed down to celebrate whilst doing so. A group of scientists from the Institute of Theoretical Astrophysics at the University of Oslo in Norway wondered what Bolt’s record could have been if he kept up his speed. Led by Hans Eriksen, they analysed television footage of the race in their spare time.

By examining the footage frame-by-frame, they found that its possible Bolt’s 9.69 seconds record could have been improved to as low as 9.55 seconds. They began by creating a standard ruler – in the form of bolts on the rail of a moving camera – from which to take their measurements, and then read off the positions of Usain Bolt as well as those of runner up Richard Thompson. Along with these they noted the time on the screen clock.

The camera angle changes from almost front-on to parallel with the track during the course of the race, so the team had to factor the uncertainty of their measurements into the figures. They could then fit a curve to the data, and estimate the distance, speed and acceleration of both runners during the course of the race. They found that the pair are neck and neck for the first four seconds, and the gold medal is “essentially won” between four and eight seconds into the race, after which point Bolt started to slow down. Interestingly, Thompson was actually going faster than Bolt at this point, but he was too far behind to catch up.

Working on two assumptions, the team calculated two potential world records. The first, in which Bolt maintains the same acceleration as Thompson for the rest of the race, nets the runner a 9.61 second world record. If he had been able to keep his acceleration 0.5 m/s2 above that of Thompson, then the time would have been 9.55. They even mocked up a picture of Bolt’s potential win:

In this mock up, the projected Bolt (right) is even further ahead of his competitors than the real Bolt (left)

Given the uncertainties in the data however, the team speculate that 9.52 seconds “does by no means seem to be out of reach.” In fact, because there was no wind at Beijing, and the International Association of Athletics Federations allows a world record to stand with a wind speed under 2 m/s, “a new world record of less than 9.5 seconds is within reach for Usain Bolt in the near future.”


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