Confessions of a Quackbuster

This blog deals with healthcare consumer protection, and is therefore about quackery, healthfraud, chiropractic, and other forms of so-Called "Alternative" Medicine (sCAM).

Sunday, January 09, 2005

Cat's Amazing Ability to Survive Falls

Have you ever wondered what happens to cats that fall from tall buildings?

Well, if they fall from above the 9th floor (9th - 32nd), 95% survive. If they fall from below the 9th floor - too bad! The most dangerous height is from the 4th floor.

This physics teacher has a nice presentation on the subject.

Terminal Velocity

Terminal velocity, a rather chilling term, describes the velocity at which drag force from the air becomes equal to the force from the weight of an object, and thus the object no longer accelerates and consequently velocity remains constant. The greater an object's cross-sectional area and the less its mass, the lower the terminal velocity and the sooner it's reached. A cat reaches its terminal velocity of 60 mph within 5 stories of freefall. For comparison, a person's terminal velocity is 120 mph.

Once a cat reaches its terminal velocity, it then begins to slow down. This is because the cat relaxes, changing its position from back arched, head down, and legs pulled tightly underneath its body, to resemble a spread eagle cat. This increases its cross-sectional area and slows the cat down. The reason for this is that our bodies are only sensitive to acceleration (this is why at times on an airplane flight it feels as if you aren't moving at all). Relaxing also causes the impact force to be spread out over more area when the cat lands, resulting in a decrease in injuries to cats' limbs when they fall seven or more stories.

Works Cited

Diamond, Jared. "How Cats Survive Falls from New York Skyscapers," Natural History 20-26; August 1989.

Diamod, Jared. "Why cats have nine lives," Nature 332, 586-587; April 14, 1988.

Fredrickson, J. E. "The tail-less cat in free-fall," The Physics Teacher. 27, 620-625; November 1989.

Halliday, David, Robert Resnick and Jearl Walker. Fundamentals of Physics, 5th ed. John Wiley and Sons, Inc., 1997.

Mehlhaff, Cheryl and Wayne Whitney. "High-rise syndrome in cats," J. Amer. Vet. Med. Assoc. 191, 1399-1403;1987.

"Terminal Velocity," Discover 9,10; August 1988.

Von Baeyer, Hans Christian. "Swing Shift," The Sciences 30, 2-4; May/June 1990.

(with thanks to Rosalind Dalefield, DVM)