We know that world records in track events are not allowed if the wind speed is above a certain amount. But suppose a 100m runner was allowed an unlimited amount of wind at his back (under his control). How fast could he run the 100m? At some point, the wind speed would knock him off his feet, and at another point, he would go flying through the air - possibly as fast as the wind is blowing - and cross the finish line at that speed.
How is the wind a factor? Does it make the runner’s steps longer for the brief time both feet are in the air?
Less drag is really cool. I once rode in the back seat of a sports car with no back seat. A couple of us sat on the back “saddle” and dangled our feet into the car. We were at a race held on an Kansas airport and were driving to another area. The driver went exactly as fast as the steady wind, maybe 25 mph. It was freaking awesome being able to move that fast with zero wind effect!
It’s only in sprints that records are not counted with too much wind. If you have to go one or more times around the track, the net effect of the wind is to hurt your speed. Basically since you are slower into the wind than with the wind at your back, you will spend more time going upwind that downwind. It’s a bit subtler, but a crosswind will slow you a bit too.
One way to think of it, is that air resistance is the product of the component of the wind that’s against you, times the total magnitude of the wind (relative to your own velocity, in both cases). And a crosswind still increases that second factor.
Distance events on the road, in order to be considered for world records, are required to be an out-and-back course (or a big loop with the start/finish within a specified distance) due to possible wind and/or elevation changes.
In belly-down freefall, a 160-pound skydiver achieves about 120 MPH. Drag scales with the square of airspeed, so as a coarse estimate, if Usain Bolt is running at 23 MPH in zero-wind conditions, he’s experiencing 160 * 23^2/120^2 = 5.9 pounds of aero drag. That much drag at that speed works out to 199 lbf*ft/sec, or 270 watts. Sprinters crank out as much as 2000 watts of power, so aero drag is a pretty large percentage of their output. The rest of their power output goes toward swinging their arms and legs: the faster you swing those heavy things, the more kinetic energy they have, and so the more power it takes from your muscles to impart that swing speed. A tailwind that eliminates aero drag leaves more mechanical power available for swinging your limbs.
At some point a limit will be reached where more tailwind doesn’t increase your speed. This happens at a forward speed where your muscles lack the strength/speed to move your legs forward fast enough to prevent yourself from faceplanting, and/or backward fast enough to actually propel you instead of slowing you down.
Has there been an analysis of Bob Beaman’s astounding long jump in 1968? It was done at altitude in Mexico City and with the maximum allowable wind of 2 mph. But still - in a sport where the record had been advancing an inch or two at a time he beat the previous record by 22 inches. Certainly the most remarkable feat in sports I have witnessed.
What are the various records on a treadmill? That’s basically what you want, a perfectly smooth “wind” that goes at the same speed you’re running at. I guess it wouldn’t work for sprints since acceleration is a factor, too.
It’s hard to even find a treadmill that can go fast enough to test the fastest runners. Usain Bolt’s max speed was 27.65 MPH. This treadmill is noteworthy for being capable of 28 MPH - and getting there in just three seconds.
I think maybe one of the big challenges in setting a treadmill record that exceeds the world’s fastest sprinters is that you need one of those world-class sprinters and one of those world-class treadmills in the same room together.