One information please

[David Rockfeller Jr]

Hello,i am new in this forum.I have seen some of yours discutions in here and i think that is a very good site for asking one question.
First of all i am sorry for writting in english but i dont know French.I olso dont know very well English but....never mind.
Well my question is:
We all know that if we have coordinate system like
(x,y,z) and x,y,z are fuctions (eatch one) of 3 others > of one other coordinate system like (u,v,w) so we can write:{x(u,v,w),y(u,v,w),z(u,v,w)},we can inverse that tranformation and write {u(x,y,z),v(x,y,z),w(x,y,z)} only if the Jacobian D(x,y,z)/D(u,v,w) it isnt 0.
Well i understand exactly the mathematical meaning of this reality and the mathematical reason that happens this but i cant understand the physical meaning when we must applicate this on physical problems.
Thank you for tell me