What do you mean in molecular physics, excitation and relaxation?

Excitation: 1. Acting on a certain system, its law of change with time does not depend on the physical quantity of the system structure and system parameters. In circuit theory, excitation often refers to the voltage of an independent voltage source and the current of an independent current source, and their time-varying law does not depend on the connection between other components in the circuit and between the components.

2. Acting on the system and provoking an external force or other input that responds to the system.

Response: The response of the system in response to an excitation. In circuit theory, the current or voltage generated by a separate power supply acting on other components is the response.

That's clear.

The motivator is not affected by the surrounding factors, while the motivated person will respond to the incentive, which is called response, and it also means that the motivator will not respond. There will be no incentive to respond.

The question is clear enough.

Tensile strength reflects the rigidity of the object, and the same as reflecting the toughness of the object, the more tensile strength it is, the more tensile strength it means (more elastic) than carbon steel, and the more tensile strength it uses is that brittle materials such as cast iron bear tensile force.

That's the unit is not the same, Sakura let the dust ideal gas slip rent often spine Zen number.

In a multiphase system, there is an unstable tendency to separate between phases due to a change in a certain environmental condition.

Strictly speaking, it does not belong to the discipline of physics, and it should be called the discipline of "physical chemistry". The simplest examples are "liquid phase" and "gas phase". That is, there is automatic separation between liquid and gaseous objects.

The structural differences between the monomers and the monomers lead to poor compatibility, resulting in microscopic phase separation.

In the process of tensile or compression, when the stress material exceeds the elastic limit in the tensile or compression process, the deformation increases rapidly, and the deformation increases rapidly after the material loses force beyond the elastic limit, and the stress resists the ability to continue to deform. When the stress reaches a certain value, the ability of the stress to resist continued deformation. When the stress reaches a certain value, the stress does not increase (or fluctuates in a small range), but the deformation stress does not increase (or fluctuates in a small range), but the deformation increases rapidly, which is called yielding.

The phenomenon of rapid growth in shape is called yielding.

Due to the presence of velocity gradients, the slower-flowing liquid layer blocks the flow of the faster liquid layer, thus. The liquid creates resistance to movement. In order for the liquid layer to maintain a certain velocity gradient motion, a reverse force must be applied to the liquid layer in contrast to the resistance.

This force exerted on a unit layer area is known as shear stress (n m2).

Shear rate (d) d=d v d x (s-1).

Shear stress and shear rate are the two basic parameters that characterize the rheological properties of a system.

Newton defined the viscosity of a fluid in the pattern of Figure 4-1. Two fluids of different planes but parallel, with the same area "a", separated by a distance "dx", and flowing in the same direction at different velocities "v1" and "v2", Newton assumed that the force to keep these different velocities proportional to the relative velocity or velocity gradient of the fluid, i.e.,

dv dx = d (Newton's formula) where is related to the properties of the material, which we call "viscosity".

Viscosity definition: two plates with an area of 1m2 are immersed in liquid, the distance between the two plates is 1 meter, if a shear stress of 1N is added, so that the relative rate between the two plates is 1 ms, then the viscosity of this liquid is.

Newtonian fluids: Fluids that conform to Newton's formula. Viscosity is only related to temperature, not to shear rate, and is directly proportional to d.

Non-Newtonian fluid: does not conform to Newton's formula d=f(d), and a represents the viscosity under a certain (d), which is called apparent viscosity.

When an object is deformed due to external factors (force, humidity changes, etc.), the internal forces that interact with each other within the object are generated, and the Sakura nucleus has long resisted the action of these external factors and tries to restore the object from its deformed position to its pre-deformed position. The internal forces on the unit surface segment product at a point in the section under investigation are called stresses. The tangent to the cross-section is called shear stress or shear stress.

Free internal rotation means that each bond in the molecular chain can rotate freely within the allowable range of the bond angle, regardless of the influence of steric hindrance on rotation, that is, there is only a bond angle limit, and there is no steric hindrance barrier. Hindered internal rotation refers to the fixed length of the key, the fixed angle of the key, but the internal rotation is hindered.

The polymer structure includes two aspects: the polymer chain structure and the aggregate state structure. The chain structure is further divided into short-range structure and long-range structure. The short-range structure belongs to the chemical structure, also known as the primary structure.

Remote structure, also known as secondary structure, refers to the size and morphology of individual polymers, the flexibility of chains, and the conformation of molecules in various environments.

The chemical composition of the chain building blocks.

The chain molecule formed by the monomer is connected by polymerization reaction, which is called the polymer chain, and the number of repeating structural units in the polymer is called the degree of polymerization.

Molecular. Generally, polymers are linear, and the molecular chain length can be curled up into a clump or stretched into a straight line.

Structure of the copolymer.

Polymers composed of two or more monomeric units are called copolymers. Different copolymer structures have different effects on material properties.

The configuration of the polymer chain refers to the geometric arrangement of the atoms fixed by chemical bonds in the molecule in space, which is stable, and to change the configuration, it must be broken and recombined through the chemical bonds. The isomers with different configurations include optical isomers, geometric isomers, and bonded isomers.

Polymer chemistry and polymer physics are the two main subjects of polymer sciencePolymer chemistry is the study of the synthesis, chemical reaction, processing and application of polymer compounds.

Polymer physics is the science that studies the physical properties of polymer substances. The main research directions include thermodynamics and statistical mechanics such as polymer morphology, polymer mechanical properties, polymer solutions, polymer crystallization, and kinetic disciplines such as polymer diffusion.

This is said separately, but "polymer chemistry and physics" is sometimes a general term for polymer chemistry and polymer physics, and sometimes refers to a major, which belongs to science, generally a graduate major, mainly studying the synthesis of polymers, mechanisms, etc., for example, the graduate students of the School of Chemistry of Jilin University have a major "polymer chemistry and physics", and its main application courses are polymer chemistry, as well as polymer physics.