Space and reference systems
The space, as the time It is somewhat difficult to define..
The space considered in mechanics as a “place” where the physical phenomena and is therefore perceived daily through l ’ experience.
It owns the properties:
Homogeneity: It says there are no privileged space homogeneous compared to other.
Isotropy: they say isotropic space where there are no directions preferred to others.
Mechanical space is homogeneous and isotropic then and is describable through Euclidean geometry.
Observing the two images we can't say so sure if the tractor to have moved, If it is the motor vehicle ’ to have moved or if you have moved both.
This doubt is due to the lack of a visual reference. The same object can be still and at rest with respect to certain topics. If we take for example an individual on a bus, He is still on the bus, but the bus will be perceived in motion by another individual who wait at the bus stop.
We are therefore able to distinguish the motion of a body only if we observe changes of position compared to other bodies, that act as reference elements. The motion then has to be considered something of its.
L ’ set of bodies or objects in respect of which we describe motion is called reference system. It is therefore useful to identify ’ collection of references the location of a body in space considered.
In physics the classical system is made up of three lines (or ACEs) mutually perpendicular to each of them.
The position (all ’ time t) a point particle is the real number that defines the distance to the source of this ’ ’ last ’ Cartesian axis along which is taken into account in that situation. This value is also called Cartesian coordinate.
The trajectory of a body is the ’ cloud of points occupied position then. From here it is worth introducing the concept of rectilinear motion.
The rectilinear motion is defined based on its trajectory, that is a straight line.
While describing the movement of the body to be an instant x(TI) in another instant x(TF) you will use the size shift , also called variation of path and described by the following mathematical relationship:
Δx (TI,TF)= x(TF) – x(TI) or rather Δx = xf – XI