The Incredible Physics of Simone Biles’ Yurchenko Double Pike



Gymnastics is an extraordinarily troublesome sport, and never simply excessive for Olympic athletes like five-time (thus far) medalist Simone Biles. The physics can be fairly difficult. Let’s take into account one thing seemingly easy, like a flip.

There can be some model of a flip in all 4 of the ladies’s gymnastics occasions: ground, bars, vault, and beam. It’s one of many two kinds of rotations a gymnast could make midair. In physics phrases, a flip is a head-to-foot rotation about an imaginary axis that runs via the gymnast’s hips. For the second kind of rotation, a twist, think about an axis that runs from their head to their toes.

Possibly it is simpler simply to see them. These two animations had been created in Python. (You may see the code right here and right here.)

Trinket by way of Rhett Allain
Trinket by way of Rhett Allain

A gymnast can truly carry out each of these kind of rotation on the identical time—that is what makes the game so fascinating to observe. In physics, we’d name such a motion a “inflexible physique rotation.” However, clearly, people aren’t inflexible, so the arithmetic to explain rotations like this may be fairly difficult. For the sake of brevity, let’s restrict our dialogue simply to flips.


There are three sorts of flips. There’s a structure, by which the gymnast retains their physique in a straight place. There’s a pike, by which they bend at a couple of 90-degree angle on the hips. Lastly, there’s a tuck, with the knees pulled up in the direction of the chest.

What is the distinction, when it comes to physics?

Rotations and the Second of Inertia

If you wish to perceive the physics of a rotation, you could take into account the second of inertia. I do know that is a strange-sounding time period. Let’s begin with an instance involving boats. (Sure, boats.)

Suppose you’re standing on a dock subsequent to a small boat that’s simply floating there, and isn’t tied up. For those who put your foot onto the boat and push it, what occurs? Sure, the boat strikes away—but it surely does one thing else. The boat additionally quickens because it strikes away. This transformation in pace is an acceleration.


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