So we have this three legged cat at our house and it limps around the place. It's missing a hing leg, and I thought it would be a good idea to strap a weight to its remaining leg so it was centered, but my flatmates said it was pointless because the cat already uses its tail as a counterweight and changing it would throw it off.

I'm not convinced, the cat seems to have a lot of trouble and it's tail surely doesn't weigh enough to offset the imbalance. Also if you press your hand against the missing leg while it's walking it will walk normally pretty much instantly. I can't attach a CONTRAPTION though because it does still need to run and jump etc. The only downside I can see to a weight is that it adds extra weight to its single leg, but maybe this would be countered by the stress taken off of it. Another downside is if this is pointless and doesn't work.

I know marmot is an ASTROPHYSICIST but maybe some of you peons can help too. Let's YaHoO answers up in here.

Attach a bouyancy balloon to the area where the leg once was.

Relocate the cat to a planet where the gravitational coefficient is lower.

Test that the cat is really disabled by revealing food by surprise and testing its speed compared to a normal cat. If the cat travels at a similar speed notify the council because it is obviously claiming benefits it is not entitled to.

Transplant a leg from another cat or similar animal.

Remove the remaining three legs and augment the cat with piezoelectric nanofibres to generate power stored in a lithium ion battery around the collar. Attach electrodes to the cat's head to analyse brain waves and synchronise detection with a pair of 12 V wheelchair motors mounted on the cat's underside.

Throw it into the street as a large car is passing and claim on their insurance to buy a new, better cat with 4 legs.

Attach an artificial leg that monitors nerve traffic around the top of the leg, powered by C02 released by solenoids, watch your cat defy those blue tits and sparrows as they are ousted from the trees in your garden.

Become your cat's best friend. Go wherever it goes and learn to communicate. If your cat needs a hand getting up the stairs, pick the little fella up and give him a lift to the top.

I had a dog once who had a crippled hind leg where he got run over by a car as a pup before I got him

he ran comically. He was the funniest dog in town. Why would you want to take that away from your cat?

A cat named George Bailey was born with only stumps for hind legs. He got around by dragging his rear end. Veterinarians and engineers from North Carolina State University tackled the problem in a new way. Instead of attaching a limb over a stump, they attached an artificial limb to his bones. The hope was that the existing bone tissue would grow around the prosthetic, a process called osseointegration. Using a cat scan of the cat, they created a model of George’s pelvis and leg bones and designed a lower leg and foot. In 2005, the team implanted a titanium post into George’s stump, to which the prosthetic leg could be attached. George was soon running and jumping on his new leg. Animals that normally walk on four legs usually get along just fine with three. George took great advantage of his new mobility, and was so rambunctious that in two months, he broke the titanium nails that were holding his leg in place. The prosthetic limb had to be removed.

Animal Prosthetics


Honestly though, there's not really much you can do for him.  My cat is missing his front left leg and gets along just fine without it.  It took him a few months to adjust, but now he's out running, jumping, and hunting like nothing happened. 

Using a cat scan of the cat

teehee

There's nothing you can really do. Your roommates are partially correct that the tail is used as a counterbalance, but that's used to prevent overrotation when its falling.

we just talked about this in physics today, strange. however it is impossible to solve this problem because we do not know the mass of the cat or the coefficient of friction between the cat and the floor.

it's a standard cat with standard cat organs etcetera. there should be a standard centre surely, like in humans it's just below the belly button (iirc) and a bit higher in men than in women.
right now it's hopping along fine but it's like a person with one leg hopping along, it might be easier if they hold a weight on the side with the leg to balance them back out.
but maybe there aren't any extra stresses from being unbalanced like this and it's fine? this is strapping a weight to a cat it's not a huge investment and if it'll make the cats life easier than i'll do it.

will it make the cats life easier or not? this is what we're discussing.

Quote

Using a cat scan of the cat

teehee

i am so happy

additional information on the subject of cats: your cat should soon learn to adjust its balance to counter-act the missing leg

it's adjusted fine it's been missing it's leg for maybe a year now, it can still get around etc FINE but i'm wondering if it could be better, really easily.

well in that case robot legs are your best bet

what!? hahah, what kind of weight do you plan on using? like canned soup? and how are you planning on attaching it? i think this sounds like a good idea for humour purposes alone.

it probably walks more easily when you press on the missing leg area because it's still shifting it's weight aroudn the way it's used to. are you sure it's not leaning on your hand when you press it there instead of leaning on what would be a leg?

If we are thinking of convoluted mechanical ways to solve this problem, a weight would be the worst place to start.

The problem isn't balance, It's just that half the cat has to be completely suspended during half of the cat's stride (which would explain the wobble. It happens as the cat lifts up the hind leg that remains). A weight would only exacerbate the problem. I'd suggest a small wheel connected to a flexible metal rod on the side of the cat that lacks sufficient leverage. Sturdy enough to provide support during a stride, flexible enough to not be noticed by the cat.

Your local engineer should be able to assist you in procuring a design and the requisite materials.

it probably walks more easily when you press on the missing leg area because it's still shifting it's weight aroudn the way it's used to. are you sure it's not leaning on your hand when you press it there instead of leaning on what would be a leg?

enough weight to counter balance a third of it's body is like three $2 coins. and yeah it's leaning against my hand, i don't see your differentiation, though iirc her stub moves so idk

this is what i'm proposing


right now it's a 4 legged chair with only 3 legs, a weight should change her into a 3 legged chair

what are the problems with this? would it be better for it?

wow these people really don't know the first fuck about physics. really, it's simple logic. study the world around you! read a book or chuck it across the room, either way you're doing physics. physics is the foundation of all sciences. physics can solve all problems. (if it can't be solved by physics, chances are it's not a real problem!).


as you can see in these diagrams, a cat uses angular momentum to rotate through space. a cat instinctively understands how to alter its distribution of weight, so that it can (ONLY in terms of its inertial frame of reference!) fly. For the purposes of this experiment only, let it be assumed that I_{exp, 1}*a is equal to the torque of the cat's tail m_2,tail on the cat's center of mass M = (m₁+m₂).

I can't correctly calculate the cat's C of M without more data, but if I'd have to make an educated guess, I would first have to split the cat into two axes: the side axis (looking at the side of the cat) and the top axis (looking at the cat from above or below). on the side axis, the C of M should be located slightly above the middle of the whole cat sans tail. this, of course, depends on the proportion of the cat's legs to its body - but if it really is a "standard cat" as you claim, my suggested C of M_side should be fairly accurate. on the top plane, the C of M should be located near the middle again, around the cat's navel.

wow these people really don't know the first fuck about physics. really, it's simple logic. study the world around you! read a book or chuck it across the room, either way you're doing physics. physics is the foundation of all sciences. physics can solve all problems. (if it can't be solved by physics, chances are it's not a real problem!).


as you can see in these diagrams, a cat uses angular momentum to rotate through space. a cat instinctively understands how to alter its distribution of weight, so that it can (ONLY in terms of its inertial frame of reference!) fly. For the purposes of this experiment only, let it be assumed that I_{exp, 1}*a is equal to the torque of the cat's tail m_2,tail on the cat's center of mass M = (m₁+m₂).

I can't correctly calculate the cat's C of M without more data, but if I'd have to make an educated guess, I would first have to split the cat into two axes: the side axis (looking at the side of the cat) and the top axis (looking at the cat from above or below). on the side axis, the C of M should be located slightly above the middle of the whole cat sans tail. this, of course, depends on the proportion of the cat's legs to its body - but if it really is a "standard cat" as you claim, my suggested C of M_side should be fairly accurate. on the top plane, the C of M should be located near the middle again, around the cat's navel.

no no no noooooooooo

are you fuckinjg retarded? go back to college.

in order to approximate the cm you have to think the cat as a thin spherical shell:



now according to gauss, inside the cat the gravitational field is proportional to the radial distance from the center of mass to the particle. like this:



so a mouse inside the tummy of a cat just when it goes to the CM is going to experience a gravitational field of zero.

you fucking idiot

just cuz you throw in your fancy diagrams does not mean its science. arent you an architecture student anyway? go back and make origami or whatever garbage you folks do

marmot you fucking idiot! stupid! ha ha, I'm just clowning around. no, I'm actually glad you're always there to bring me back down to earth! aaaaaa you dope.

Quote from: earl on April 09, 2009, 04:19:20 am

wow these people really don't know the first fuck about physics. really, it's simple logic. study the world around you! read a book or chuck it across the room, either way you're doing physics. physics is the foundation of all sciences. physics can solve all problems. (if it can't be solved by physics, chances are it's not a real problem!).


as you can see in these diagrams, a cat uses angular momentum to rotate through space. a cat instinctively understands how to alter its distribution of weight, so that it can (ONLY in terms of its inertial frame of reference!) fly. For the purposes of this experiment only, let it be assumed that I_{exp, 1}*a is equal to the torque of the cat's tail m_2,tail on the cat's center of mass M = (m₁+m₂).

I can't correctly calculate the cat's C of M without more data, but if I'd have to make an educated guess, I would first have to split the cat into two axes: the side axis (looking at the side of the cat) and the top axis (looking at the cat from above or below). on the side axis, the C of M should be located slightly above the middle of the whole cat sans tail. this, of course, depends on the proportion of the cat's legs to its body - but if it really is a "standard cat" as you claim, my suggested C of M_side should be fairly accurate. on the top plane, the C of M should be located near the middle again, around the cat's navel.

no no no noooooooooo

are you fuckinjg retarded? go back to college.

in order to approximate the cm you have to think the cat as a thin spherical shell:



now according to gauss, inside the cat the gravitational field is proportional to the radial distance from the center of mass to the particle. like this:



so a mouse inside the tummy of a cat just when it goes to the CM is going to experience a gravitational field of zero.

you fucking idiot

interesting, I had thought of the shell method as well. unfortunately I am one step ahead of you again old chum!let's take another look at figure 1, shall we? study the image closely, for if you are too brief you may miss what is actually accuring:

this "mouse" you speak of shows up in reality as well, in the form of a small pod the cat instinctively ejects from its feet. this gives the cat's body sufficient speed and angular momentum to overcome both the forces of gravity g and air pressure to effectively somersault into an upright position mid-air.