The Speed of the Cheetah
The fastest land animal alive
At the 2009 IAAF World Championships, Usain Bolt showed the world his amazing ability to run 100 meters in 9.58 seconds. While his average running speed in this event was 37.58 km/h, his top speed was an astonishing 44.72 km/h.
While Usain Bolt is in all probability the fastest human ever to have lived, his speed record is dwarfed by that of the fastest land animal alive: the cheetah. In 2012, 11-year-old cheetah Sarah set the cheetah 100 meter record at 5.95 seconds, with a top speed of 98 km/h. How can this cat run so fast, and why did it evolve this ability?
How the cheetah runs so fast
To be able to attain any top speed, an animal must be able to maintain acceleration long enough to reach that speed. The following part is a bit theoretical, but not more so than high school physics.
Newton’s second law states that force equals mass times acceleration, from which it directly follows that acceleration equals force divided by mass. Note that we are talking about the resulting force on the animal: opposing forces (friction with air and ground) are subtracted from the force the cheetah exerts on the ground. The force of friction gets higher when speed increases — meaning accelerating when going 80 km/h is harder than accelerating when…
