From Knowable magazine, July 10:
Cats twist and snakes slide, exploiting and negotiating physical laws. Scientists are figuring out how.
Isaac Newton would never have discovered the laws of motion had he studied only cats.
Suppose you hold a cat, stomach up, and drop it from a second-story window. If a cat is simply a mechanical system that obeys Newton’s rules of matter in motion, it should land on its back. (OK, there’s some technicalities — like this should be done in a vacuum, but ignore that for now.) Instead, most cats usually avoid injury by twisting themselves on the way down to land on their feet.
Most people are not mystified by this trick — everybody has seen videos attesting to cats’ acrobatic prowess. But for more than a century, scientists have wondered about the physics of how cats do it. Clearly, the mathematical theorem analyzing the falling cat as a mechanical system fails for live cats, as Nobel laureate Frank Wilczek points out in a recent paper.
“This theorem is not relevant to real biological cats,” writes Wilczek, a theoretical physicist at MIT. They are not closed mechanical systems, and can “consume stored energy … empowering mechanical motion.”
Nevertheless, the laws of physics do apply to cats — as well as every other kind of animal, from insects to elephants. Biology does not avoid physics; it embraces it. From friction on microscopic scales to fluid dynamics in water and air, animals exploit physical laws to run or swim or fly. Every other aspect of animal behavior, from breathing to building shelters, depends in some way on the restrictions imposed, and opportunities permitted, by physics.
“Living organisms are … systems whose actions are constrained by physics across multiple length scales and timescales,” Jennifer Rieser and coauthors write in the current issue of the Annual Review of Condensed Matter Physics.
While the field of animal behavior physics is still in its infancy, substantial progress has been made in explaining individual behaviors, along with how those behaviors are shaped via interactions with other individuals and the environment. Apart from discovering more about how animals perform their diverse repertoire of skills, such research may also lead to new physics knowledge gained by scrutinizing animal abilities that scientists don’t yet understand.
Critters in motion....
....MUCH MORE
Related from January 2022 and earlier:
Questions America Wants Answered: Can The Fed Engineer A Soft Landing?
Via Stock Cats:
"can the Fed engineer a soft landing ?" pic.twitter.com/gDsLDChilA
— . (@StockCats_2009) January 10, 2022
That is a fortunate cat. As we have seen in other studies, for a cat four stories are very survivable and ten stories are survivable but in-between, say five to seven stories,the risk almost doubles.
Dead Cat Bounce: What is the Terminal Velocity of a Cat?
Original post:)
This morning Improbable Research brings us:
Dropping and bouncing cats
A small collection of items about dropped and bounced cats:
1. ”Does a Cat Always Land on Its Feet?” [article in Annals of Improbable Research, vol. 4, no. 4]And the headline story, originally posted October 4, 2010:
2. The Cat Bounce web site.
3. Dead Cat Bounce, the stock market metaphor.
4. The physics of skulking and falling cats.
(Thanks to investigator John Runions for suggesting the conjunction of #1 and #2.)
What is the Terminal Velocity of a Cat?
I don't know, let's ask a physicist.
From the University of Alaska, Fairbanks:
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.Professor Puss-Puss demonstrating L=mvr:
**This graph is taken from "How Cats Survive Falls from New York Skyscrapers." It plots the percentage of adult humans and cats killed by a fall versus the stories fallen. The adult human graph increases steadily to 100% while the cat graph increases to about 10% and then decreases to about 5% for falls from 7 to 9 stories. Although the graph doesn't show it, the survival rate holds steady at 95% from 9 to 32 stories.
Not only do cats seem to "understand" how increasing their area can lead to a less painful landing, they also seem to be well acquainted with the conservation of angular momentum, which they artfully use to land on their feet time and time again.
:The paper that made curiosity about falling cats a legitimate area of academic study:
High-rise syndrome in cats (1987)Which supplied the data illustrated by the curve, above.
However, as The Straight Dope points out:
...The potential flaw is this: the study was based only on cats that were brought into the hospital. Clearly dead cats, your basic fell-20-stories-and-looks-like-it-came-out-of-a-can-of-Spam cats, go to the Dumpster, not the emergency room. This may skew the statistics and make falls from great distances look safer than they are....Research at the University of Zagreb, "Feline high-rise syndrome: 119 cases (1998-2001)" was inconclusive on the cat-in-a-dumpster hypothesis.
I believe this demonstrates that most market drops are survivable.
Next: The Bounce....
If interested see also "Does a Cat Always Land on Its Feet?" at The Annals Of Improbable Research (link rotted so via the Internet Archive)
