Cat Feet or Buttered Bread

Cat Feet and Buttered Bread

An old wives’ tale goes something like: cats always land on their feet.
First, I wanted to test this experiment. So I took my sister’s cat (a morbidly obese cat, by the way) and dropped him from our second story balcony. He hissed at me before the fall, but ran away uninjured. If this orange doorstop of a cat can land on its feet, then all cats can, too.
But why?
My roommate claims there’s some weird physics term involved. My mother says that it’s something about the cat’s skeletal system or something. And my sister thinks that cats have a weird organ in their brains. So who’s right? Any of them? All of them?

Angular Momentum:
The physics term that my roommate couldn’t remember is angular momentum. Angular momentum is the measurement of how an object circles around a reference point (1). With a cat, the angular momentum is related to the mass of the cat. So what’s this have to do with cat’s falling? The conservation of angular momentum. At the final point during his fall, the cat has zero angular momentum. First he manages to right himself by rotation through a series of back curves and hip rotations (2). Then he’s able to conserve his angular motion and not to turn around again.
This is a diagram of how a cat rights himself and then conserves angular momentum (2): 

But how does the cat actually end up conserving his angular momentum? The cat is able to twist the bottom half of his body in the opposite direction of the top part of his body, therefore conserving angular momentum, having zero angular momentum (3).

Skeletal System:
What my mom meant about the skeletal system is that the cat has a special system that makes it easier for the cat to initially right itself. What makes the cat’s system special? For one thing, the cat doesn’t have the same collarbone that we humans do (4). The cat’s collarbones are tiny and, the cat’s shoulder blades are attached by muscles and not bone. These qualities help Mr. Cat right himself in mid-flight.
The cat also has a very flexible backbone. The vertebrae have especially elastic cushioning between each other, lending to greater flexibility in the spine and in his front limb movement, aiding the cat in making sure that his feet are underneath his body for the optimum landing.

Vestibular Apparatus:
So how does a cat actually know which way to right itself during a fall? I look at it like this: the cat has his very own level in his ears. It tells him which way is down and which way is up, therefore how to position his body. The vestibular apparatus is an organ that actually can be found in a cat’s ears. This organ is filled with fluid and made of hair-lined chambers. Tiny crystals float in the fluid. And the hair lining the chambers is extraordinarily sensitive (5). When the cat moves, the crystals resonate against the cat’s ears, telling the cat his body position and from there, which way is up. Knowing which way is up and his body position, the cat is able to right himself and land on his front paws.

High-Rise Incidents:
Two veterinarians have discovered that if a cat falls from seven stories or less, the shorter the distance, the higher the cat’s survival chance. But they’ve also discovered the opposite to be true of any fall higher than seven stories. Why does a cat have a higher survival rate when thrown off the tenth floor instead of the eighth floor? During a fall, scientists claim that at about the seventh floor for most cats, the cat reaches his terminal velocity. This means that the cat is falling as fast as he is going to fall. At this point, the cat’s body relaxes. This relaxation releases stress from the cat’s body and thusly his body is able to better absorb the impact of the fall (5).

Butter or Cat?
So old wives’ tales claim that a cat will always land on his feet. But another old wives’ tale claims that if you drop a piece of bread, it will always land on the buttered side. So if you tie a piece of buttered bread to a cat’s back, which side will land? That’s the topic of my next research paper.

(1) http://en.wikipedia.org/wiki/Angular_momentum
(2) http://web.hep.uiuc.edu/home/g-gollin/dance/dance_physics.html
(3) http://www.rose-hulman.edu/~moloney/AppComp/2001Entries/e05fi/catsfeet.htm
(4) http://www.ccmr.cornell.edu/education/ask/index.html?quid=600
(5) http://www.bestfriendspetcare.com/cat-behavior/catslanding2.cfm