A gymnast can really carry out each of all these rotation on the similar time—that is what makes the game so attention-grabbing to observe. In physics, we might name one of these motion a “rigid body 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 format, 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 direction of the chest.
What is the distinction, by way of physics?
Rotations and the Second of Inertia
If you wish to perceive the physics of a rotation, it’s good to 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. Should you put your foot onto the boat and push it, what occurs? Sure, the boat strikes away—nevertheless it does one thing else. The boat additionally quickens because it strikes away. This variation 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. Should you put your foot on it and push it, utilizing the identical pressure for a similar period of time as you probably did for the smaller boat, does it transfer? Sure, it does. Nevertheless, it would not 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 alter an object’s movement. Typically 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).
While you push on the boat, we will describe this force-motion interplay with a type of Newton’s Second Regulation. It appears like this:
Illustration: Rhett Allain
