Why does a cat almost always land on its feet when it falls from a height?
Turn a cat over so its belly is facing up, drop it from about half a meter, and when it lands, it still lands on its feet. How did it turn around?
In 1894, French physiologist Étienne-Jules Marey used continuous photography to record the entire process of a cat in midair. His conclusion was that the cat completes its turn while still in the air—without pushing off from anything.
The difficulty is physics: at the moment you let go, the cat has no initial rotation. By conservation of angular momentum, it should keep not rotating. In 1969, two Stanford engineers provided the answer. The cat bends its body into two sections: the front legs pull in tightly against its chest, while the hind legs push off. The tightened front half spins faster, and the opened hind half spins slower. The two halves twist in opposite directions, and since they rotate by different amounts, the total angular momentum adds up to exactly zero. The whole process takes about 0.3 seconds, and a drop of just 30 centimeters is enough—kittens only three or four weeks old can do it. The tail isn’t a “rudder”; tailless cats can still right themselves.
In mechanics, this question has a formal name: the “cat dropping problem.” Later, people even borrowed it to study how satellites adjust their orientation.
What other things have cats done that made you feel they weren’t being scientific?
Turn a cat over so its belly is facing up, drop it from about half a meter, and when it lands, it still lands on its feet. How did it turn around?
In 1894, French physiologist Étienne-Jules Marey used continuous photography to record the entire process of a cat in midair. His conclusion was that the cat completes its turn while still in the air—without pushing off from anything.
The difficulty is physics: at the moment you let go, the cat has no initial rotation. By conservation of angular momentum, it should keep not rotating. In 1969, two Stanford engineers provided the answer. The cat bends its body into two sections: the front legs pull in tightly against its chest, while the hind legs push off. The tightened front half spins faster, and the opened hind half spins slower. The two halves twist in opposite directions, and since they rotate by different amounts, the total angular momentum adds up to exactly zero. The whole process takes about 0.3 seconds, and a drop of just 30 centimeters is enough—kittens only three or four weeks old can do it. The tail isn’t a “rudder”; tailless cats can still right themselves.
In mechanics, this question has a formal name: the “cat dropping problem.” Later, people even borrowed it to study how satellites adjust their orientation.
What other things have cats done that made you feel they weren’t being scientific?
