The concept a material point came to us from physics. The nature has no natural material points, this concept from area of abstraction. For calculation of the done way, it is possible to present the car as a material point because its scales it is incomparable are small with scales of the passable distance.
For a start it is necessary to find out what is a material point. The body can be taken for a material point if by the sizes it is insignificant in comparison with the passable distance. In such situation neglect when calculating any qualities of a body - its form and the sizes.
Conditions under which the car becomes a material point
If to present what distance will pass the car in several hours from the moment of a start of motion, then it becomes clear – own sizes of the car in comparison with the passable piece of a way allow to consider it a material point in relation to this distance.
At the same time, if the car makes overtaking maneuver, then it cannot be considered as a material point any more. There is a distance at which there is an overtaking, it is possible to commensurate with the car sizes. It is enough to pass two or three lengths of the overtaken car to overtake it. Such sizes can be compared, and both the distance of overtaking, and the car size are significant.
Thus, the car can be considered as a material point when determining a way if certain conditions are met.
Main definitions of a material point
Speaking to physics language, a body which sizes for this task do not matter, it is possible to call a material point. This body can have some weight, but almost zero or very small size.
It is impossible to call a material point natural size, it is an abstract object with which it is possible to operate when calculating as comparative size (very big and very small). In the nature any body has certain sizes which cannot be neglected.
This concept is created for simplification of calculations, for example, at rotation around the axial value. It is also possible not to take into account wheel speed, at calculation of speed of the body. The abstract concept is collective for all parts of the body recognized as a material point and is separately simply inexpedient to consider them.
Example when the body is considered material
The car overcomes distance from one city in another. To calculate the average speed of the movement of the car, it is considered as a material point.
However, if there is a purpose, in details to investigate the movement of parts of the car, for example each wheel separately, the car will not be a material point any more.
When overtaking is made, all distances and sizes are proportional, according to a material point is not present. Everything depends on concrete application of sizes for the solution of a certain task. Emergence of a material point is influenced by relative comparison of the sizes involved in process.