When solids interact with various environmental factors, changes can occur - both internal and external. One example is the mechanical stress that appears in the bowels of the body. It determines the degree of possible changes in case of damage.
Basic concepts in physics
Mechanical stress is a measure of the internal forces of an object, which occurs under the influence of various factors. For example, when deformation occurs, during which external forces try to change the relative position of particles, and internal forces prevent this process, limiting it to a certain value. Thus, we can say that mechanical stress is a direct consequence of the load on the body.
There are two main types of mechanical stress:
- Normal - applied to a single area of the section along the normal to it.
- Tangent - attached to the section area tangent to it.
The set of these stresses acting at one point is called the stress state at this point.
Measured in pascals (Pa), mechanical stress: the calculation formula is shown below
Q=F/S, Where Q is mechanical stress (Pa), F is the force generated inside the body during deformation (N), S is the area (mm).
Properties of solids
Solids, like all others, are made up of atoms, but they have a very strong structure that is practically not subjected to deformation, i.e. volume and shape remain constant. Such objects have a number of unique properties that can be divided into two large groups:
- Physical.
- Chemical.
Physical include the following:
- Mechanical - study them with the help of the appropriate impact on the body. These properties include elasticity, brittleness, strength, i.e. everything related to the ability to resist deformation caused by external factors.
- Thermal - study the effect of different temperatures on an object. These include expansion when heated, thermal conductivity, heat capacity.
- Electrical - these properties are associated with the movement of electrons inside the body and their ability to gather into an ordered stream when exposed to external factors. An example is electrical conductivity.
- Optical - studied with the help of light fluxes. These properties include light reflection, light absorption, diffraction.
- Magnetic - determined by the presence of magnetic moments in the components of a solid body. For them, as well as for electrical ones, they are answered negatively.charged particles due to their structure and certain motion.
Chemical properties include everything related to the reaction to the impact of the relevant substances and the processes occurring in this case. An example is oxidation, decomposition. The structure of the crystal lattice also refers to these properties of the object.
You can also select a small group of physical and chemical properties. It includes those that are manifested both under mechanical and chemical effects. An example is combustion, during which changes occur in the two above characteristics.
