If a shape (a cube, say) is moving in one direction and cannot be stopped, and another cube, in the way of this one, is still and cannot be moved, what happens on collision?

I can't answer it myself :/

Well

If an object 'cannot be stopped' then it must have a force acting upon it during the collision, of an infinite magnitude. The second object that cannot be moved must also have a force, acting as a reaction force of equal magnitude to the first object, in the opposite direction. These forces will cancel out, to a net force of zero, and they will stop.

Which contradicts the necessary property of the moving cube, therefore this hypothetical situation is impossible.

Of course if you were actually able to subtract infinity from infinity the end result would be undefined, so this is really more of a guess...No one you ask will have a true answer just matters of opinion

We know that the equation inf-inf=0 is flase because if we add any number to both sides...

10+inf-inf+0+10

You get inf-inf=10...

because adding 10 to infinity just becomes infinity and thus your equation has been proven to be untrue


Whereas take another commonly believed equation:

inf-inf=inf

Still makes little sense, because this would dictate that:
Inf-2inf=0

Of course multiplying inf by 2 just gives you inf again and your equation becomes familiar:

Inf-inf=0

Which we have already proven to be false

Your answer is undefined...

This post was edited by kruikoi on Jul 17 2009 09:33am

this is how technoviking was born

Lol funny as hell

I decide not to answer

It's not subtracting infinity from infinity, it's subtracting a sufficiently large number from infinity to equal zero.

That is, they both do not apply an infinite force on each other, the moving cube applies a force on the stationary cube, which the stationary cube then matches and supplies in the opposite direction, resulting in a net force of zero, as defined by a cube that cannot be moved(has an unlimited capacity to supply a reaction force).

eg:

10N-->|(unmovable wall)
means there is a <--10N reaction force, and the net force and hence acceleration is zero.

Using your maths, this model of the problem means that, where original force =x and reaction force =y

x=y
x-y=0

add the concept of infinity and

inf-y=0

y will scale up to whatever number infinity is, which is impossible, which is exactly why this scenario is impossible, as there is a contradiction in anything that can provide an infinite force.

facepalm......

Of course nothing can provide an infinite force anyway, as F=ma, and it would require an infinite amount of either mass, which there isn't, or an infinite amount of acceleration, which is dv/dt, v being limited by c, being also impossible.

this is an insanely stupid and easy question. it all depends on how you define "cannot be stopped" -- either that means the cubes both have an energy that increases to surmount any obstacles (infinity) meaning that they'll both come to a halt OR the cubes phase through each other...there is no possible other answer.

for those of you who tried to do math with infinity please realize that it isn't a set number -- therefore in this case you have to define it as a number that can increase simply to keep the object moving...

I stated that the answer was undefined......

and its basic logic to assume that adding or subtracting anything from infinity would still be infinity...

Such a number as described simply isnt possible...

This post was edited by kruikoi on Jul 19 2009 12:26am

The bold defies the principles of the first cube...

And the math makes no sense... the only way for anything to be completely and utterly unstoppable or immovable by any force would have to posess a force equal to infinity..