A gymnast can really carry out each of all these rotation on the identical time—that’s what makes the game so fascinating to observe. In physics, we might name any such motion a “inflexible physique rotation.” However, clearly, people aren’t inflexible, so the arithmetic to explain rotations like this may be fairly sophisticated. For the sake of brevity, let’s restrict our dialogue simply to flips.
There are three sorts of flips. There’s a structure, wherein the gymnast retains their physique in a straight place. There’s a pike, wherein they bend at a few 90-degree angle on the hips. Lastly, there’s a tuck, with the knees pulled up in the direction of the chest.
What’s the distinction, by way of physics?
Rotations and the Second of Inertia
If you wish to perceive the physics of a rotation, you should take into account the second of inertia. I do know that’s 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. In case you put your foot onto the boat and push it, what occurs? Sure, the boat strikes away—however it does one thing else. The boat additionally hurries up because it strikes away. This modification in pace is an acceleration.
Now think about that you simply transfer alongside the dock and decide a a lot bigger boat, like a yacht. In case you put your foot on it and push it, utilizing the identical drive for a similar period of time as you probably did for the smaller boat, does it transfer? Sure, it does. Nevertheless, it doesn’t enhance in pace as a lot because the smaller boat as a result of it has a bigger mass.
The important thing property on this instance is the boat’s mass. With extra mass, it’s tougher to vary an object’s movement. Generally we name this property of objects the inertia (which isn’t to be confused with the second of inertia—we’ll get to that quickly).
Whenever you push on the boat, we are able to describe this force-motion interplay with a type of Newton’s Second Legislation. It seems to be like this:
Illustration: Rhett Allain
