Why do four legged tables rock

We didn't have that right? So if if we had this this sorry, this leg and this one perfectly in line with each other. And we had these two, maybe one, a bit shorter and another bit taller than we would have one plane determined by these three and one plane being determined by these three.

And they would be different planes, Right? So maybe if this one is the shorter one, then we have a plane that goes something like this, right? Because the chair wants to till this way.

And if we have this one maybe being a bit shorter than we would have something. A plane that wants to be like this because the chair wants to tilt to the right.

So we have two planes here in this case, that kind of colliding with each other, right? The chair doesn't know where to go. So what kind of wobbles in between those two plans? Not for the stool. For stool, No matter what length you set the feet too. Are the legs too? You always have only one unique plane being determined on your floor.

So no wobbling involved. Explain why the hypotenuse of a right triangle must always be longer than ei… If you stand facing a wall with your toes touching the wall, you cannot rais… Suppose you stand flat-footed, then you rise and balance on tiptoe. If you s… Place a heavy book on a table and the table pushes up on the book. Why doesn… As you stand on a floor, does the floor exert an upward force against your f… Explain why more energy is needed to walk up stairs than to walk horizontall… As the upper platform of the movable staircase is raised and lowered, the he… Problem You are designing the living room of an apartment….

View Full Video Already have an account? Luca A. Problem 47 Hard Difficulty Explain why a four-legged chair may rock from side to side even if the floor is level. Answer No; Three points define a plane, so the legs of the three-legged chair will always meet in the flat plane of the floor.

View Answer. Topics Foundations for Geometry Geometry Basics. Section 1 Points, Lines, and Planes. Discussion You must be signed in to discuss. Top Geometry Educators Catherine R. Semantic enigmas. The body beautiful. Red tape, white lies. Speculative science.

This sceptred isle. Root of all evil. Ethical conundrums. This sporting life. Stage and screen. Birds and the bees. Roger Hudson, Brampton Canada Because a balance on two legs of a 3-legger would require the centre of gravity to be perfectly balanced between two legs i. It would also need to be thus balanced under variable and moving weight demands - all but impossible.

So a balance is found - with the flat seat at a slight angle - where three legs are fixed, i. On a 4-leg, any three legs can meet the countours of a vaguely even floor with the seat at a similar angle but movement of the mass on the seat will shift the equilibrium to an alternative settling point: on a 3-leg, there IS no alternative, because 3 legs can only make one combination of three.

M B Drennan, Oxford UK Because of the mathematical principle that any three points must always lie in the same plane, whereas this is not necessarily true for four points. Remembering seeing something similar in Italy as a kid read a fair time ago! Not sure if it was the same concept as this, but remember thinking it was a very simple mechanism doing something magical.

Not as elegant but the tables were rock steady on the uneven pavement - more like cobble stones. Bruce H. Anderson July 28, PM. Great idea, keeps the table from rocking - but does it also keep the table surface level? I mean, of course it won't if you put it on a sloping surface, but on a relatively level surface? Inquiring minds want to know!

PlanetPapi July 28, PM. Most people will be satisfied with available solutions like folded paper or a wedge. If you own a restaurant with 50 tables, would you pay extra for each one? Rocking table would be the last thing on your mind. It appears that the inventor has other valid patents than this one. Also there are other similar, "cost adding" solutions available. I love the video portion where they show an -already- -broken- stem on a wine glass fall over.

I call FOUL! I'm frugal, so I install adjustable feet on the tables I have if there's a problem. It's a new patent, so expect to pay an arm, a leg, and your firstborn for one of these. No price is shown on the site, so you know what that means. AllanDallyn July 28, PM. My son visualizes complex problems in 3 dimensions to, and he has ADHD I think they have this in common.

Nik August 18, AM. This seems like a solution looking for a problem. A three legged table does not have to be 'unstable and easy to knock over' just spread the legs wide enough. I've had experience with antique three legged tables, and modern versions, and they function admirably. I just find this ingenious. Sure, you have the old solutions: three legs, screw out legs and what have you.