A gymnast can really carry out each of a lot of 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 difficult. For the sake of brevity, let’s restrict our dialogue simply to flips.
There are three sorts of flips. There’s a structure, through which the gymnast retains their physique in a straight place. There’s a pike, through which they bend at a couple of 90-degree angle on the hips. Lastly, there’s a tuck, with the knees pulled up in 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 must contemplate 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. If you happen to 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 hurries up because it strikes away. This transformation in pace is an acceleration.
Now think about that you just transfer alongside the dock and choose a a lot bigger boat, like a yacht. If you happen to put your foot on it and push it, utilizing the identical power for a similar period of time as you probably did for the smaller boat, does it transfer? Sure, it does. Nonetheless, it doesn’t improve 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 harder to alter 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).
If you push on the boat, we will describe this force-motion interplay with a type of Newton’s Second Regulation. It appears to be like like this:
Illustration: Rhett Allain
