How Do You Determine the Worlds Fastest Man?

Last Updated on November 16, 2011 by Jimson Lee

Back to School Special, Part 1. Warning: this subject matter may bring back horrible memories of high school physics!

How do you determine the Worlds Fastest Man?

• The Winner of the 100m Olympic Gold Medal (The Olympic shortest sprint distance)?
• The fastest 10m segment? (with or without a running start?)
• A radar gun (like a police radar) at an instantaneous point of time?

They all are based on time over distance.

The 100m time also includes acceleration out of the blocks for almost two-thirds of the race, so the peak speed would be recorded around the 60 meter mark. In Tyson Gay or Usain Bolt’s case, it’s more like 65 meters.

The term “Velocity” can be broken down into 3 components:

• Average velocity
• Instantaneous velocity
• Speed

I used the terms quicker and faster when discussing then Moye blocks. You can be quick, but not fast. You can be fast, but not quick. Then there’s the trade-off between being too quick or too powerful out of the blocks..

The problem with being quick, like the Moye blocks, is you are standing up sooner and have better leg turnover, but no power. It’s like pushing a car stuck in the snow. Are you vertical, or more horizontal for more power?

Imagine you are a car with 5 gears. You have to optimize when to shift gears.

The term “Faster” means either “farther” (greater distance) or “sooner” (less time).

In order for you or me to calculate the speed of an object, we must know how far it goes AND how long it takes to get there. When you ask “how far”, are you referring to the distance or the displacement?

Thus,

Speed is the rate of change of distance with time.
Velocity is the rate of change of displacement with time.

Remember high school or college physics? Speed is a scalar and velocity is a vector.

Speed gets the symbol v (italic) and velocity gets the symbol v (boldface).

Thus, the instantaneous speed of an object is the magnitude of its instantaneous velocity where:

v = |v|

The distance is fixed, the measurement is time

The average sports fan and TV viewer prefers (at least conceptually) the measurement of time. Of course, the average television fan doesn’t consider other factors such as wind, altitude, track surface, or modern technology such as speed suits or high tech sprint spikes.

But we really should be using velocity.

The problem with measuring time is it doesn’t show the whole picture. There are many components to 100 meter race.

In track, ideally a 10 meter segment can be used, only if official splits are setup. Video analysis are not accurate unless you have the same setup for every race. Video analysis is accurate when used among different athletes in the same race (like the IAAF biomechanical studies)

Then again, they don’t give gold medals to the fastest 10 meter segment. Or who can bench press the most before the race. This isn’t STREND!

It doesn’t take much to figure out that the secret of a great 100m time is reaching top speed (acceleration), a fast top speed (maximum velocity), and maintaining that top speed (speed endurance). Perhaps splitting atoms is easier?

0.83 sec/10 meters translates to 12 meters per second (m/s) or almost 27 miles per hour (mph) or 43 kilometers per hour (kph).

Very few elite sprinters have reached the 12 m/s “speed limit”, that list includes Tim Montgomery, Maurice Green, and Ben Johnson. Of course, add today’s superstars like Asafa Powell, Tyson Gay and Usain Bolt.

Only in Beijing 2008 did we see Usain Bolt drop that to 0.82 sec/10 meters, then dropping again to 0.81 sec/10 meters in Berlin 2009.

Additional Physics References:
http://physics.info/velocity/
http://physics.ucsc.edu/~josh/6A/book/notes/node12.html