What is called mechanical movement? What is a material point and in what case the body can be taken

What is called mechanical movement? What is a material point and in what case the body can be taken as a mat. point for what this concept was introduced? What is a frame of reference? Why is it being introduced? What coordinate systems do you know? What is called the trajectory of movement? What is path and travel? What is the difference between a path and a move?

Mechanical movement is a change in the position of bodies (or body parts) relative to each other in space over time. To describe mechanical movement, it is necessary to choose a frame of reference.

A material point is a body whose dimensions can be neglected under these conditions. This model is used in cases when the linear dimensions of the bodies under consideration are much less than all other distances in the given problem or when the body is moving translationally.

The reference system is the coordinate system associated with the reference body and the chosen way of measuring time. The x coordinate of point Μ is the projection of the end of the radius vector of point Μ onto the Ox axis. Usually a rectangular coordinate system is used. In this case, the position of the point Μ on the line, plane and in space is determined, respectively, by one (x), two (x, y) and three (x, y, z) numbers – coordinates. The path s is a scalar physical quantity determined by the length of the trajectory described by the body over a certain period of time. The path is always positive: s> 0. Displacement of the body over a certain period of time is a directed segment of a straight line connecting the initial (point M0) and final (point M) position of the body.