If two perfectly round spheres were to touch each other, how large would the contact surface be?
>>7956350
nothing ever really touches.
>>7956351
2spooky4me
Is this a physics question or is this a math question?
>>7956351
>>7956357
Yes
>>7956350
Mathematically speaking, they will only touch at a single geometric point in space therefore having no area, length or volume.
0 m^2
If said spheres are elastic, then hertzian contact theory applies
>>7956389
In doing so they'd loose their status as a perfect sphere.
>>7956350
If these are idealized mathematical spheres, then 0. If they are physical spheres, then they don't exist.
>>7956350
the diameter of the nucleus of whatever element the balls are made of
>>7956467
>>7956350
I don't know if the spheres in pic related are magnets, but if they are i have one like thoses and they are fucking fun to play with
>>7957011
they are yeah
i was going to buy them but i remembered i still have a couple of hard drives in here and i would probably wreck everything if i started leaving rolling magnets around the place
>>7957024
You don't have to worry if the hard drives are 50 cm away from the magnets, especially if they are ferrite magnets.
I was literally playing with neodymium magnets in my computer desk, and nothing happened
>>7957046
they do look fun
ok
It depends on the properties of the material at the atomic scale.
Nothing more can be said.
>>7956350
they don't touch
pauli exclusion principle
>>7956350
THEY"RE TOPOLOGICALL CONEX
>>7956350
What if two perfectly, phallic-shaped penises tough each other anon? I bet you know that answer.
>>7959297
Touch
>>7959357
>Physicsphile
HAHAHAHAHA
>>7959357
>autistic physics fag gets upset when he is asked to define contact based on his models the video
meme models never.
>>7957024
You can still buy them, just not as toys.
>>7956462
>If they are physical spheres, then they don't exist
So if my car had 4 perfectly round, completely inelastic, totally smooth tires driving on a perfectly smooth, inelastic road I'd have zero contact with the ground, zero ground traction and thus I'd have a hover-car.
That's what I've gathered from this thread so far.
I suppose it'd be zero as any given point on a sphere is just a 1d point. Two 1d points in contact are just that.
1 rawr budi
>>7959357
Electromagnetic force keeps everything from ever touching. If this force didn't repel one object from another on a molecular level you could run your hand through a door like nothing was there. It just depends on how you define touching.
>>7959494
No. In the standard model of friction, friction is independent of contact area. Even if it was dependent on area, you could probably make some derivation based on the fact that you have a line in contact with the ground.
>>7957011
I too, love to play with balls.
>>7956350
I'll ask my nut-sack.
>>7959357
The take away message from that is that "touching" on the classical level doesn't really mean anything at the quantum level.
>>7959357
that video literally says that nothing ever touches, but we are going to conveniently redefine what the concept of touching means because we dont like it for our OCD perfect world view
Like how 1 is "not a prime number" even though it totally is.
Non-existent, but not quite.
>>7960060
>friction is independent of contact area
>>7956350
[math]0.\overline{0}1nm^2[/math]
>>7956411
Perfect spheres do not exist.
>>7960195
>I have too many sticks up my butt to have fun
>>7960248
but that is true, retard.
the force of friction depends on the normal force and the coefficient of friction, nothing else, when you are talking about two relatively smooth/flat surfaces in contact with each other.
>>7959498
>1d
it's 0d
>>7960698
Why is it 0d? It has length from centre, so it's 1d
>>7960243
Units are not prime you fucking savage.
I'm done guys, fuck this.
>>7959494
They have to be some stiffass tires then to not give way
>>7956350
First of all you need to define when something is touching another thing, then we can talk.
From a mathematical viewpoint however the answer is simple; they would touch only at a singe point... That is an infinitely small point
>>7956359
Kek
one atom?
>actually nothing touches
rather than square meters, the contact area would just be a number
Mathematically they don't touch
Physically they don't touch either
>>7962537
You aren't even wrong.
It's about tree fidy
>>7962130
Is an infinitely small number different to zero?
>>7962761
No, it's a dimensionless point; it has 0 diameter and thus no area.
>>7961972
Space is 3D, plane is 2D, line is 1D, dot is 0D
>>7962775
so are they touching or not?
>>7963408
*to clarify - exactly 0% of the surface area is touching, so why do we say it is touching?
>>7963411
But there is one point in space where the distance between the spheres is zero
>>7963414
maths is weird
so what's the numerical answer? so far all the posts have been conspiracy theories
>>7962130
this, right? the extent of the surface in contact would actually be one point right?
Could we say, for the purposes of this question, that our perfect spheres are made from infinitely small, electromagneticly natural particles?
>>7962537
The answer would be 1 right?
>>7960328
Doesn't matter.
OP asked about when two perfect spheres touched, not when two imperfect spheres touched. Did you fail reading comprehension, you fucking retard? If you can't come up with an answer to the question asked, then don't post, fagtron
>>7956350
balls don't touch, it would be gay
>>7960243
>1 is a prime
go ahead, what's the unqiue prime factorization of 4 then?
>>7965580
quality post!
>>7959494
Doesn't understand the friction from the contact area is necessary to move the car
>>7960328
>if
0 [AREA UNITS].
Only a single point is shared. There is no "contact surface" because a surface is a 2 dimensional figure, while a point is 0 dimensional.
>>7959494
Yes
Now go and try making a single perfectly round, completely inelastic, totally smooth tire
>>7956350
Since spheres dont actually exist, its a moot point
>>7956357
>Perfectly round spheres
What do you think?
>>7956350
Two perfect spheres would have no contact area, they wouldn't even make a noise when they touched
>>7960243
A prime has two and only two distinct factors
>>7956350
Nothing is perfectly round
Pi is infinitely repeating, so a perfectly round sphere would have to be infinitely accurate.
>>7956350
You meant to say two non deform-able spheres. Deformation will increase the contact area to a value dependent on mass, velocity, and deformation coefficients.
>>7969017
Unless you're talking about instantaneous area of contact with respect to time, which is infinitesimal for all spheres at the moment they meet. Which is a dumb thing to even consider. You're dumb.
>>7968926
>they wouldn't even make a noise when they touched
this is extremely cool if true
>>7962130
> infinitely small point
M8 when's the last time you saw a radically sized point
>>7956350
> dA
>>7956351
I figured this out when I was 6
>>7968926
It doesn't make sense to talk about mathematically perfect shapes and sound as if they exist in the same universe
>>7960412
Friction is independent of contact area only for large areas or infinitely inelastic materials. For small areas, you're going to hit the finite elasticity or strength of the materials, or their other properties.
perfect spheres can't exist in reality idiots
If two sets of points satisfy the definition of a sphere in 3-dimensional Euclidean space, then we could say that they touch if their intersection is nonempty. The only possible finite cardinalities for the intersection set of the two spheres are 0 and 1. All other possible intersections are infinite.I could prove this statement, but I don't feel like it. If we're not talking about mathematical spheres, all bets are off.
