According to a BBC report, scientists have calculated that less than 8% of Usain Bolt’s running effort goes to motion and the rest overcomes aerodynamic drag.
The team calculated that Bolt’s maximum power occurred when he was less than one second into the race and was only at half his maximum speed. This demonstrates the near immediate effect of drag, which is where air resistance slows moving objects.
Usain Bolt. (Photo: smokeghost via Flickr)
They also discovered less than 8% of the energy his muscles produced was used for motion, with the rest absorbed by drag.
When comparing Bolt’s body mass, the altitude of the track and the air temperature, they found out that his drag coefficient – which is a measure of the drag per unit area of mass – was actually less aerodynamic than that of the average man.
OCW and MITx offer great opportunities to better understand the often surprising field of aerodynamics, including OCW’s 16.100 Aerodynamics materials and the upcoming MITx MOOC 16.101x Introduction to Aerodynamics.
I wonder how fast he would be able to go without the drag coefficient.
Without drag, he would theoretically be able to reach all the time infinitely closer to light speed. though actually accelerating to that speed might take significantly longer than the expected lifetime of the universe.
Add: Though that is only assuming that he could constantly use 100% of his energy for movement.
Since the faster he goes, the more friction his muscles will actually do. And sooner or later his brain will stop being able to follow at his speed so rather more seriously, there are limits. Just not very practical ones 🙂
kamal
I imagine 12.5 times as fast because 12.5 x 8% = 100%
Except that he can’t breathe in space.
can he go without only air friction, by any means….