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Topic: Why cats survive falls (Read 1471 times) |
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rhinoceros
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Why cats survive falls
« on: 2003-06-19 10:25:25 » |
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Who needs nine lives?
http://www.newscientist.com/lastword/article.jsp?id=lw1018
Question:
A friend of mine reckons that you can drop a cat from any height and it will survive unhurt because its terminal velocity is lower than the speed at which it can land unhurt. Can someone confirm or refute this because the kittens in my house now look strangely at my friend. I'm sure this can't be true, can it?
Anna Goodman , Oxford, UK
Answers:
I'm reminded of a study reported in the Journal of the American Veterinary Medicine Association in 1987 by W. O. Whitney and C. J. Mehlhaff, two New York vets, entitled "High-rise syndrome in cats". The study was also summarised in Nature a year later.
Briefly, the authors examined injuries and mortality rates in cats that had been brought to their hospital following falls ranging from between 2 and 32 storeys. Overall mortality rates were low, with 90 per cent of the cats surviving, a fact that supports the correspondent's ailurophobic friend. However, the study unexpectedly found that the incidence of injuries and death peaked for falls of around seven storeys, and then actually decreased for falls from greater heights.
The Nature article presents three main variables that determine injury and mortality rate the speed reached by the moggy, the distance in which said moggy is brought to a stop, and the area of moggy over which the stopping force is spread. While concrete streets work in nobody's favour when it comes to stopping falling items, cats suffer relatively little injury (compared to their owners) because they do indeed reach lower terminal velocities and absorb the shock of stopping so much better. A falling cat has a higher surface area to mass ratio than a falling human, and so reaches a terminal velocity of about 100 kilometres per hour (about half that of humans). They are also able to twist themselves so that the impact is spread over four feet, rather than our two. And as they are more flexible than humans, they can land with flexed limbs and dissipate the impact forces through soft tissue.
To answer the paradoxical increase in survival rates once seven storeys has been reached, the authors suggested that an accelerating cat tends to stiffen up, reducing its ability to absorb the impact. However, once terminal velocity is reached, there is no longer any net force acting on the cat, and so it will relax, increasing both its flexibility and the cross-sectional area over which the impact is dissipated once the cat hits the ground.
I'd still keep your friend away from your kittens, if I were you. Few buildings in your home town of Oxford are seven storeys high, but there are plenty of rivers about.
John Bothwell , Marine Biological Association, Plymouth, Devon, UK
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[rhinoceros] Here is a left brained joke among the answers:
I don't know what the terminal velocity of the average cat is ,but this question did remind me of a joke.
Because cats always land on their feet and toast always lands buttered side down, you can construct a perpetual motion machine by simply strapping a slice of buttered toast to a cat's back. When the cat is dropped it will remain suspended and revolve indefinitely due to the opposing forces.
Catherine , Staffordshire University, Stoke-on-Trent,UK
================================
[rhinoceros] And here is a more generalized try:
The risks to different animals of taking a fall were laid out in 1927 by the biologist J. B. S. Haldane, in Possible Worlds and Other Essays. He wrote: "Gravity, a mere nuisance to Christian, was a terror to Pope, Pagan, and Despair. To the mouse and any smaller animal it presents practically no dangers. You can drop a mouse down a thousand-yard mine shaft; and, on arriving at the bottom, it gets a slight shock and walks away.
"A rat is killed, a man is broken, a horse splashes. For the resistance presented to movement by the air is proportional to the surface of the moving object. Divide an animal's length, breadth, and height each by ten; its weight is reduced to a thousandth, but its surface only to a hundredth. So the resistance to falling in the case of the small animal is relatively ten times greater than the driving force. An insect, therefore, is not afraid of gravity; it can fall without danger, and can cling to the ceiling with remarkably little trouble."
John Forrester , Edinburgh, UK
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DrSebby
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Re: virus: Why cats survive falls
« Reply #1 on: 2003-06-20 04:23:23 » |
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...i recall hearing that after reaching terminal velocity, the relaxed cat
tends to stretch out or become more limber, thus acting as a sort of
parachute mechanism and actually slowing the cat's velocity.
DrSebby.
"Courage...and shuffle the cards".
----Original Message Follows----
From: "rhinoceros" <rhinoceros@freemail.gr>
Reply-To: virus@lucifer.com
To: virus@lucifer.com
Subject: virus: Why cats survive falls
Date: Thu, 19 Jun 2003 08:25:26 -0600
Who needs nine lives?
http://www.newscientist.com/lastword/article.jsp?id=lw1018
Question:
A friend of mine reckons that you can drop a cat from any height and it will
survive unhurt because its terminal velocity is lower than the speed at
which it can land unhurt. Can someone confirm or refute this because the
kittens in my house now look strangely at my friend. I'm sure this can't be
true, can it?
Anna Goodman , Oxford, UK
Answers:
I'm reminded of a study reported in the Journal of the American Veterinary
Medicine Association in 1987 by W. O. Whitney and C. J. Mehlhaff, two New
York vets, entitled "High-rise syndrome in cats". The study was also
summarised in Nature a year later.
Briefly, the authors examined injuries and mortality rates in cats that had
been brought to their hospital following falls ranging from between 2 and 32
storeys. Overall mortality rates were low, with 90 per cent of the cats
surviving, a fact that supports the correspondent's ailurophobic friend.
However, the study unexpectedly found that the incidence of injuries and
death peaked for falls of around seven storeys, and then actually decreased
for falls from greater heights.
The Nature article presents three main variables that determine injury and
mortality rate the speed reached by the moggy, the distance in which said
moggy is brought to a stop, and the area of moggy over which the stopping
force is spread. While concrete streets work in nobody's favour when it
comes to stopping falling items, cats suffer relatively little injury
(compared to their owners) because they do indeed reach lower terminal
velocities and absorb the shock of stopping so much better. A falling cat
has a higher surface area to mass ratio than a falling human, and so reaches
a terminal velocity of about 100 kilometres per hour (about half that of
humans). They are also able to twist themselves so that the impact is spread
over four feet, rather than our two. And as they are more flexible than
humans, they can land with flexed limbs and dissipate the impact forces
through soft tissue.
To answer the paradoxical increase in survival rates once seven storeys has
been reached, the authors suggested that an accelerating cat tends to
stiffen up, reducing its ability to absorb the impact. However, once
terminal velocity is reached, there is no longer any net force acting on the
cat, and so it will relax, increasing both its flexibility and the
cross-sectional area over which the impact is dissipated once the cat hits
the ground.
I'd still keep your friend away from your kittens, if I were you. Few
buildings in your home town of Oxford are seven storeys high, but there are
plenty of rivers about.
John Bothwell , Marine Biological Association, Plymouth, Devon, UK
=============================
[rhinoceros] Here is a left brained joke among the answers:
I don't know what the terminal velocity of the average cat is ,but this
question did remind me of a joke.
Because cats always land on their feet and toast always lands buttered side
down, you can construct a perpetual motion machine by simply strapping a
slice of buttered toast to a cat's back. When the cat is dropped it will
remain suspended and revolve indefinitely due to the opposing forces.
Catherine , Staffordshire University, Stoke-on-Trent,UK
================================
[rhinoceros] And here is a more generalized try:
The risks to different animals of taking a fall were laid out in 1927 by the
biologist J. B. S. Haldane, in Possible Worlds and Other Essays. He wrote:
"Gravity, a mere nuisance to Christian, was a terror to Pope, Pagan, and
Despair. To the mouse and any smaller animal it presents practically no
dangers. You can drop a mouse down a thousand-yard mine shaft; and, on
arriving at the bottom, it gets a slight shock and walks away.
"A rat is killed, a man is broken, a horse splashes. For the resistance
presented to movement by the air is proportional to the surface of the
moving object. Divide an animal's length, breadth, and height each by ten;
its weight is reduced to a thousandth, but its surface only to a hundredth.
So the resistance to falling in the case of the small animal is relatively
ten times greater than the driving force. An insect, therefore, is not
afraid of gravity; it can fall without danger, and can cling to the ceiling
with remarkably little trouble."
John Forrester , Edinburgh, UK
----
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"courage and shuffle the cards..."
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Tywick
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Re:Why cats survive falls
« Reply #2 on: 2003-06-24 05:02:51 » |
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Great job explaining how they survive falls. How is it you think they survive ceiling fans?
Example: http://msnug.com/misc/kitty.html
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