Morning study

Fluid mechanics is the branch of physics concerned with the mechanics of fluids (liquids, gases, and plasmas) and the forces on them.  It has applications in a wide range of disciplines, including mechanical, aerospace, civil, chemical and biomedical engineering, geophysics, oceanography, meteorology, astrophysics, and biology. A fluid is a substance that does not have a specific shape, but rather takes the shape of its container and is characterized by its ability to flow. Therefore, the expression includes liquids and gases and is divided into two parts: Compressible fluids are fluids whose density changes with the change in pressure applied to them, such as gases Incompressible fluids are fluids whose density does not change with the change in pressure on them, such as fluids. Fluid Mechanics can be divided into fluid statics, the study of fluids at rest; and fluid dynamics, the study of the effect of forces on fluid motion. 

The strength of a material is defined as its capacity to sustain a load without breaking or undergoing significant plastic deformation in the field of materials mechanics. The study of forces acting on a material and the resulting deformations is known as "strength of materials." When a force is applied to a mechanical component, the resulting internal forces are measured in units called stresses. All kinds of deformation, up to and including total breaking, may result from stresses acting on the material. When the amount by which a material is stretched or compressed is measured in units, the term "strain" is used to describe the substance's deformation. Evaluation of a mechanical member's load capability requires calculation of the stresses and strains produced inside the member. To do so, it is necessary to provide a detailed description of the member's shape, restrictions, loads, and material attributes. Tensile or compressive axial loads, as well as rotary loads, may be applied (strength shear). Calculating the stress and strain at each place inside a member is possible given a full description of the loading and the geometry of the member. Knowing the stress and strain inside a member allows one to determine that member's strength (load bearing capability), stiffness properties, and stability (ability to keep its original shape). Calculated stresses may be compared to the member's material yield or ultimate strength. It is possible to compare the member's computed deflection to use-based deflection criterion. The applied load may be compared to the buckling load of the member, which can be determined. The dynamic response of the member may be computed using the member's stiffness and mass distribution, and then compared to the acoustic environment in which the member will be employed. When discussing material strength, engineers often refer to the yield stress, which is the stress at which a material deforms beyond the point where the deformation can be restored to its original shape simply by removing the pressure. Maximum allowable stress is what we mean when we talk about a material's ultimate strength. Strength at fracture is defined as the stress level at which fracture begins (the last stress value recorded).