Jul 29, 2013
From todays news and views......
You've likely heard that cats always land on their feet, but while felines have extraordinary gravity-defying abilities, they don't always safely nail the landing.
Most of the time, a falling cat will land on its feet, but the height of a cat's fall plays a role in how likely it is to right itself and absorb the shock of the landing without injury.
A cat's innate ability to reorient its body during a fall is called the righting reflex, and it's observable in kittens as young as 3 weeks old. By 7 weeks, this skill is fully developed.
The physics of a falling feline
French scientist Etienne Jules Marey tested the reflex in 1890 by dropping a cat and using his chronophotographic camera to capture up to 60 consecutive frames a second of the cat's fall. Afterward, he was able to watch in slow motion how the cat began to shift its balance the second the fall began.
A vestibular apparatus in a cat's inner ear acts as its balance and orientation compass so that it always knows which way is up. Once a falling feline has determined which part of its body should be facing up, it rotates its head to see where it's going to land.
Next, the cat's spine comes into play. Cats have a unique skeletal structure consisting of no collarbone and an unusually flexible backbone with 30 vertebrae (humans have 24). A feline's backbone allows it to correct its position during freefall.
As its back arches, the cat positions its front feet under him with the front paws close to the face to protect it from impact. When he lands, the leg joints bear the weight of the impact.
Like flying squirrels, cats have a low body-volume-to-weight ratio, which allows them to slow their velocity when falling.
Not all falls are equal
A cat's ability to right itself midair and safely land on its feet is certainly impressive, but certain falls can be dangerous - or even deadly - for a cat.
Typically, felines that fall from greater heights, such as more than five floors, tend to suffer less severe injuries than those falling from just a couple stories. The longer freefall gives cats more time to right themselves and position their bodies correctly.
In 1987, New York City's Animal Medical Center conducted a study of felines that had fallen from tall buildings. While 90 percent of the animals survived, most suffered serious injuries, but the cats that fell from heights of seven to 32 stories were less likely to die than those that fell from two to six stories.
The buttered cat paradox
Just as a cat almost always lands on its feet, it's pessimistcally accepted that buttered toast will always land butter-side down.
Toast, of course, lacks a righting reflex, so its tendency to land butter-side down can be attributed to the fact that it usually falls at an angle and most dining tables are about waist high. Therefore, when the buttered toast slips from a plate, it can manage only half a rotation before hitting the floor.
The buttered cat paradox arises when you consider what would happen if you attached a piece of buttered toast to a cat's back and then dropped the feline.
According to the faux paradox, the cat's fall will slow as it nears the ground and the animal will begin to rotate. Eventually, it'll come to a stop but hover over the ground as it perpetually turns from cat-feet side to buttered-toast side.