As of 20 August 2008, Usain Bolt is the the world's fastest man with a 200 meter sprint of 19.30 seconds, giving an average speed of 10.36 meters per second. There are 1609.344 meters in a mile, so 10.36 m/s / 1609.344 m/mi = 0.0064374 miles/second. There are 3600 seconds in an hour, so 0.0064374 mi/s * 3600 s/hr = 23.175 miles/hour. Usain Bolt clocked an *average* speed of 23.175 mph during his world record run, however he may have achieved speeds of 23-27 mph in the early part of the sprint.
The U.S. is growing, and the world is growing faster. (Andreas Kermann/iStockphoto) The U.S. entered 2016 with an estimated population of 322,762,018 according to an end-of-year estimate from the U.S. Census Bureau, meaning that we added more than 2.4 million people to the population over the course of the year.
By 1900, the U.S.A. population jumped to 75,994,575. In 1920 the census counted more than a hundred million people (105,710,620). Another 100 million people were added to the United States population in just fifty years when the two hundred million barrier was reached in 1970 with 203,302,031 counted in the census. The 2000 Census counted a U.S.A. population of 281,421,906. Six years later the U.S. population had grown to 300 million.