Why a cat always land on its feet!?

Why do cats always land on their feet? This is a question that drove 19th century scientists crazy. Until one of them used an unexpected tool to solve the mystery: a camera. Étienne-Jules Marey was an obsessive scientist and inventor who analyzed the motion of things. And he began experimenting with photography at a time when the medium was mostly used to document static objects.

But his goal was to capture movement. And he did it by following the basic principle of photography: exposing light-sensitive material to light and then covering it in darkness. So his way of creating this darkness and light was a plate with holes. Marey was able to capture motion on a single sheet of glass by directing light as the object moved across the frame. Basically, he just blocks the light from time to time. The disc opens and then comes darkness as the man moves, opens, darkness. The technique is called chronophotography, and the results reveal something the human eye can never see on its own: individual steps of movement.

A few years later, Kodak introduced celluloid film, and Marey decisively updated his coin camera. He replaced one sheet of glass with a roll of film that moved between exposures. So lighten up: the picture is taken. Darkness, the film progresses. The light, the image - so it's a film camera, that's what it is. Marey made many films for research purposes and even tried throwing other animals to see if they would land on their feet, especially this rabbit and chicken. Which brings us back to the cat.

It seems to be able to correct itself by twisting in the air without pushing anything forward that would violate the law of conservation of momentum. Sounds scary, but hang in there. One of Newton's laws of motion states that something in motion cannot simply stop unless acted upon by an opposing force. Basically, you can't just change direction in mid-air, Wile E. Coyote-style. But to the naked eye it looks like a cat. Most people thought the cat was "cheating" by knocking off the person's hand, but Marey's film showed what actually happens.

The first shots immediately prove that a cat does not start its cycle with a kick. But it has a curved back. And bending over, he divides his body forward and backward, and both parts can function independently. You know how a figure skater pulls his arms to spin faster? That happens here too. At the beginning of a spin, the cat pulls the front legs in and lets the back legs out so that the front can turn quickly while the back remains relatively still. Then halfway through it works the other way around. Front legs extended, back legs tucked in to turn one side of the body.

And you'll notice that when the cat lands, all four legs are extended as far as possible, which means a slow turn. So the cat rolled, but not generally; both sides work in reverse. It uses the inertial force of its own body weight to turn both sides. And since the two spins work in separate opposite directions, they cancel each other out.

So Newton's law is not violated. Marey published his results in Nature in 1894, solving the falling cat problem for the first time. His work is an early example of the use of photography for scientific discovery. What does photography do for science? It saves something and makes it persistent so you can analyze or share it later.

But Marey showed something that the eye could not see - never. You may have seen another famous early example of motion photography: In 1878, Eadweard Muybridge used 12 cameras connected by trigger wires to demonstrate that a horse lifts all four feet off the ground at some point during a gallop.

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