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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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ScienceShot: The Physics of Usain Bolt
25 July 2013 7:15 pm
In the summer of 2009, during the World Championships in Athletics in Berlin, Jamaican sprinter Usain Bolt set a world record time of 9.58 seconds for the 100-meter dash—but he did so with a slight wind at his back. Now, a new analysis suggests that Bolt’s time without the tailwind would still have been a record-setter. Researchers used weather conditions during the race to estimate Bolt’s coefficient of drag, which is related to his body’s wind resistance. That parameter, along with data about the sprinter’s position (collected by lasers every 0.1 second during the race), suggests that Bolt’s time sans wind assistance would have been 9.68 seconds, the researchers report today in the European Journal of Physics. That’s 0.1 seconds slower than the official result but still good enough to squeak past Bolt’s previous world record time of 9.69 seconds, which he had set at the Beijing Olympics the year before. Race data also show that Bolt sprang from the starting blocks with an acceleration of 9.5 meters per second squared—that’s almost 0.97 g, the acceleration due to Earth’s gravity—and was churning out a whopping 2.6 kilowatts of power (3.5 horsepower) less than 1 second later.