# Geometric point of view of configuration space and Lagrangian mechanics

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Even though (I think) I understand the concept of a tangent bundle, I have trouble assimilating the idea of the configuration space being one and in relation to what that is the case. How can I understand that intuitively (but with formal basis, if possible)?

For instance, here's a generality I can't understand:

Sundermeyer (Constrained Dynamics, page 32) states:

The configuration space itself is unsuitable in describing dynamics [...]. One needs at least first order equations, and geometrically these are vector fields. So we have to find a space on which a vector field can be defined. An obvious candidate is the tangent bundle $TQ$ to $Q$, which may be identified with the velocity phase space. [...]. Lagrangian mechanics takes place on $TQ$ and $TTQ.$

This post imported from StackExchange Physics at 2016-07-04 12:09 (UTC), posted by SE-user Mario Barela

Comment to the post (v6): It seems that Sundermeyer with the last sentence just wants to say that velocity and acceleration belong to $TQ$ and $TTQ$, respectively.
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