It is a riddle.
It is the strongest force,
to resist your force,
and yet it is not a force.
It never accelerates,
but it is always moving.
It never rests, and
it never gets tired.
It has been defined many ways,
but no one can quite capture it.
What is it?

(In reply to A Comment by Michael Cottle)

Michael Cottle, you really did not need to mention me.

pcbouhid, I understand your posting but I unfortunately don't speak/write portuguese.  Anyway, when problems are on 30, they seem to speed up.  And you posted most of them together, so they will keep appearing one after another.  You are in for a busy time.  I try to post a problem every two weeks or so. 

Just a question, can you explain how I knew that  Paulo César was your first name?

Posted by Hugo on 2005-04-29 23:03:45