homemade radar, a very basic device capable to measure Doppler shift and thus velocity of a target. Of course we had to try and bring the radar to the hockey game to collect some data. The colour plot above shows one minute of radar data. The colour scale is in m/s. For comparison: 5 m/s equals 18 km/h or 11.2 mph; last night in the London 2012 Olympics, Usain Bolt won gold over 200 m with a time of 19.32 s, which means an average of 10.35 m/s, and even more impressively, David Rudisha broke his own world record over 800 m and won gold with a time of 1:40.91, which averages at 8.93 m/s. The radar data suggests that some of the scientists moved even faster. This might be due to several reasons: during the hockey game, there wasn't one distinct radar target, but 12 players, many of which would be in the radar beam (or a side lobe) simultaneously. Moreover, the players are waiving their arms and hockey sticks about, creating an amplitude modulation on top of their own speed, a bit like the heavy ion in a cloud of thermal electrons. Also, during the game, the players do run only for very short distances, and thus these very short bursts of high speed may well exceed the speed of sprint athletes, who have to keep up a fast pace for the duration of the race.
Radar data: Phil Erickson; photos and time lapse: Thomas Ulich.