The Subject of Mechanics

Mechanics was born at the dawn of civilization. As a science, mechanics deals with the motion of masses and the effect of forces in causing or modifying these motions.

Classical mechanics can be divided into statics and dynamics. Statics studies bodies at rest, or in motion at a constant speed and in a constant direction. Dynamics is the study of bodies that undergo a change of speed or direction, or both, because of forces acting upon them. There are three branches in mechanics:

1) statics which deals with forces acting on and in a body at rest;

2) kinematics describes the possible motions of a body or a system of bodies;

3) kinetics attempts to explain or predict the motion that will occur in a given situation.

During the 100 years following Newton's death, the development in mechanics was due to its progressive mathematization. In 1788, Louis Lagrange published his "Mećhanique analitique", which treated mechanics as a branch of mathematics, arising from a few axioms and developed entirely by analytical mathematical techniques. Mechanics has continued to be a branch of mathematics, but it also returned to its roots in physics in the 19th century. Andrée-Marie Ampére used experiment to discover aspects of electrical science that could be treated by mechanical mathematics. The kinetic theory of gases provided new physical measurements and concepts that could be mathematized and handled by mechanics. But here individual bodies or elements could no longer be treated as it was impossible to follow an individual gas molecule. Instead, large groups were the subject of mechanical operations, and statistical mechanics was born.

All this work was done within the Newton's framework, which proved too narrow by the beginning of the 20th century. In the 1920s a special mechanics called quantum mechanics was devised to deal with subatomic particles. This mechanics is completely mathematical: it consists of the mathematical computation of the probability of making a physical measurement.

In the ordinary world Newtonian mechanics still holds and serves to direct everything from the design of new automobiles and aircraft to the navigation of intercontinental ballistic missiles and satellites. Mechanics helps further progress in many scientific and engineering fields. Its achievements are used to create new machines and aircrafts, calculate the orbits of spaceships, study ocean currents and forecast the weather.

Of eleven departments in the faculty of Mathematics at Rostov State University, two belong to the Division of Mechanics: the Department of Elasticity and the Department of Hydromechanics. These two departments give lectures on the theory of plates and shells, the theory of plasticity, the stability of elastic systems, dynamics of viscous fluid, the stability of motion, gas dynamics and the plane problem of hydromechanics. The scientists in the department use the asymptotic method for solving the problems of strip wedge layers. They also investigate the contact problems of bodies of non-classical shape. All these problems are very important, especially in machine building. Hydroaeromechanics studies the laws of the mechanical movement of a substance in its three states: liquid, gas and solid. The range of problems examined by hydroaeromechanics is very wide and interesting. Calculations in the aircraft industry, weather-forecasting, examining sea currents, and monitoring the stars are all impossible without using the main laws of hydroaeromechanics.

The demands which the specialist in the field of hydroaeromechanics must satisfy have greatly increased. For example, when calculating the movement of a spaceship in the period of its re-emergence in the atmosphere, one must take into account complicated physical and chemical transformations which take place in the hot gas around the ship. In other words, he must be able to solve complex mathematical problems and then use modern calculating machines.

The Department of Theoretical Hydroaeromechanics gives training in four scientific areas. The first of them is connected with the problems of hydroaeromechanics and the theory of elasticity. The department also investigates the problem of liquid and gas lubricants. The third scientific trend is the study of the waves on the surface of liquid. It is of particular importance in determining the influence of waves on various technical constructions.

Another area of research deals with complex problems of mechanics of compact environments. This is of great importance for constructing hydrofoils.

3.2 What new facts about the science of mechanics have you learnt from the text?

Поиск по сайту: