Exercise 5

Write the plural of the following nouns; read and translate them into Russian:

force- principle- phenomenon-

body- engineer- mixture-

beam- member- lump-

term- analysis- quantity-

Exercise 6

Match the word in bold with their meanings:

1. The study of the motion of rigid bodies is a significant topic in engineering mechanics. Mechanics belongs to a group of subjects.

2. The nuclear forces are relatively weak.

3. The diameter and length of the column are determined by the quantity of material to be absorbed.

4. The use of mass spectrometer in analysis enables one to determine the components of mixtures.

5. The maximum weight of the wall allowed is 22000 kg.

1. how long something is

2. the amount that something weighs

3. the science concerning forces and the material bodies

4. strength; power

5. a lump of something; a large quantity

Exercise 7

Read and translate the text. Be ready to discuss it .

Structural mechanics

Mechanics is the science concerning forces and the resulting motion of material bodies that are subjected to various kinds of forces. There are certain basic laws, or principles in mechanics that enable the skilled user to determine, for example, the manner in which a body would move or deform, given the nature and distribution of forces acting on it a knowledge of its physical characteristics. Conversely, if one had an accurate knowledge of the actual state of deformation in a body, one would be able to predict exactly the forces acting on the body at any time.

It is a common experience for everyone that forces applied to structural members, such as beams, produce deformations in these members. We know that when a heavy load is placed on the floor of a structure supported by beam, the floor and the beam deflect slightly in the direction of the load. A structural engineer who knows the principles of mechanics that govern the phenomenon would be able to predict what would happen to the structural member when a known force or set of forces acts on it; he would be able to predict how much deflection the structural member would experience at any point. Occasionally the reverse problem is of interest to the engineer. By means of accurate measurements the deflections that occur in a structural member may be known for a number of points. This information, plus the knowledge of certain basic principles, enables the engineer to determine the forces that act on the members and cause the measured deformation.

As in many fields of engineering, the primary goal of mechanical analysis is to predict the behavior of a system that has not yet been built or tried out. Structural mechanics can be defined as a science dealing with calculation of structures for strength, fixity and stability. We’ll discuss the four basic quantities used in the study of mechanics- force, mass, length and time.

For example, force is a quantity with which everyone is familiar. It is a push or a pull exerted on an object by means of a person or some other physical agency. Force results from direct contact between one body and another, or from remote influences such as gravity, electric or magnetic fields.

Mass is another basic quantity in mechanics. Mass must not be confused with weight. Weight is a force, whereas mass is a measure of how great an effect a force may have on the object. It has been stated that the result produced by the application of force on physical bodies may be first of all deformation, as in a structural member. Either effect requires the measurement of length, or of length and time. Length is an arbitrary linear measure; all lengths being relative to the basic physical dimensions of some accepted standard.

Time is a measured duration. Most engineers are primary concerned with the development and design of structures and products of various kinds. Since these constructions are usually subjected to internal forces and deformations called stresses and strains, the properties of materials under the action of these stresses and strains for various environments become an important engineering consideration. A thorough knowledge of material stress-strain behavior is required by the engineer so that failures can be avoided. Such knowledge is also necessary in order to utilize materials most economically. In addition to the mechanical or stress-strain properties, the designer must consider all physical and chemical properties in the selection of a material and the size of a member. Physical properties of materials include, in additional to the mechanical properties, the thermal, electrical, and acoustical properties. Important chemical properties of materials include the resistance of materials to various types of corrosive environments.

Notes to the text:

structural member элемент конструкции

structural engineer инженер-строитель

reverse problem обратная задача

physical agency физическое влияние, действие