2Solid in Space. Efforts and Links: Power
The motion of a body depends on the actions that its environment exerts on it. The elements developed in Volume 1 of this series have led us to the movement equations, and we now need to describe this environment, that is the forces and efforts of all types that are being exerted on the solid during its motion and condition it, in particular the instantaneous energy or power that are dispelled or exchanged. Knowing this power is a crucial step towards establishing the movement equations; but to assess it, we still need to know and describe the environment where a body is located and moving. This is the object of this current chapter.
2.1. Degrees of freedom of a solid
In a Galilean frame
, the situation of a solid (S) is defined by six parameters; they are, for example, the three coordinates of its center of inertia G, that is the three components of the position vector
, and the three Euler angles which express the orientation of the basis joined to the solid. And these six parameters form the maximum independent ones likely to describe the situation of a solid.
Independent means that there is no relation linking them when describing the situation of the solid. The movement equations will establish this link subsequently, once the environment ...