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Wed 4 May, 2011 06:08 am
If a perfectly round and perfectly hard ball is resting on a perfectly flat and perfectly hard surface, how much of the ball is in contact with the surface?
@engineer,
...
how much is that one point, though?
@hamilton,
Steady now.....you are getting into the mathematics of "different sized infinitessimals" which put Georg Cantor into a mental institution !
Maths is full of ridiculously "perfect" objects like "flat surfaces" and "non-deformable spheres". They are merely models which give approximations to real life statics and dynamics.
@hamilton,
The one point is infinitely small.
The intersection of a plane and a sphere chosen at random in a space is either zero (no intersection), a point, or a circle smaller than or equal to the diameter of the sphere. Sounds like your case is one point.
@raprap,
ok. how would the third one work out. ive never heard it put like that.
@hamilton,
Picture a plane going
through the ball. The intersection is a circle.
@engineer,
ooohhh.... ok. i see now. i was thinking of a 2d plane, but your talking 3d. ok.