Hi, I'm a bit confused wit the concept Configuration Space. First, the professor defined generalised coordinates as such: U got a system of n particles, each particle has 3 coordinates(x,y,z), so u got 3n degrees of freedom. If the system has k holonomic constraints, u got 3n-k degrees of freedom. Instead of working with cartesian coordinates, we now define a new set of coordinates q1,q2,..,q3n-k. These are the generalised coordinates of the system,3n-k in total. I get this. Then a little bit further, when explaining Hamilton's Variatonal Principle, he defines a Configuration Space. "The configuration space of a system is a 3n-k dimensional space with the generalised coordinates on the coordinate-axes." So far, so good. On the reference list of this course,Classical Mechanics of Goldstein is listed. First page of the second chapter of Goldstein: This n-dimensional space is therefore known as the configuration space... In classical mechanics from Kibble, I didn't even found such thing as config space. Also, on the internet I've found another course of Classical Mechanics: http://www.phys.ttu.edu/~huang24/Teaching/Phys5306/CH2A.pdf" [Broken] There they say Here they say n generalised coordinates in n dimensional space, not like according to my professor 3n-k dimensions with 3n-k generalised coordinates! Also, there's a little graph with on the horizontal axis q1 and on the vertical axis q2, but there are n dimension, according to their course !!! But for the axes only q1 and q2 is used, so why not qn-1 and qn. But a graph with only two axis, is 2-dimensional right? It is not ndimensional See my frustration here? Please help me.