The interaction of solids with different environmental factors, changes can occur - both internal and external.One example is the strain that appears in the depths of the body.It determines the extent of the possible changes is damaged.
basic concepts in physics
Mechanical stress - a measure of the internal forces of the object, which occurs under the influence of various factors.For example, when a strain, in which external forces are trying to change the relative position of the particles, and internal - hinder the process, limiting it to any particular value.Thus, we can say that the mechanical stress - a direct result of the load on the body.
There are two main types of stress:
- Average - applied per unit area of the cross section normal to him.
- tangent - is attached to the platform section at a tangent to it.
combination of these stresses acting at one point called the state of stress at that point.
measured in Pascals (Pa) mechanical stress: calculation formula is shown below
Q = F / S,
where Q -Mechanical stress (Pa), F - the force that occurs in the body during deformation (H), S - area (mm).
properties of solids
Solids, like everyone else, are composed of atoms, but they have a very solid structure, which is practically not subjected to deformation, ie,volume and shape remain constant.These objects have a number of unique properties that can be divided into two major groups:
- physical.
- Chemical.
For individuals include the following:
- Mechanical - study them with the corresponding effects on the body.These properties include elasticity, fragility, solidity, i.e.everything that is connected with the ability to resist deformation caused by external factors.
- Heat - studying the influence of different temperatures on the subject.These include the expansion on heating, thermal conductivity, heat capacity.
- Electric - these properties are related to the movement of electrons within the body, and their ability to assemble into an ordered flow under the influence of external factors.Example - the electrical conductivity.
- Optical - studied with the help of light flows.These properties include light reflectance, light absorption, diffraction.
- Magnetic - determined by the presence of the magnetic moments of the components of the solid.For them, as well as for electrical and respond negatively charged particles due to its structure and certain movements.
The chemical properties include everything associated with the response to the impact of the relevant substances and processes that occur at the same time.Example - oxidation degradation.The structure of the crystal lattice also relates to these object properties.
You can also select a small group of physico-chemical properties.This includes those that appear as by mechanical or by chemical exposure.Example - burning, during which changes occur in two above characteristics.
