THE MODERN ENGINEERING PROFESSION
The result of the increase of scientific knowledge is that engineering has become an essential profession.Until the nineteenth century engineers were for the most part craftsmen or project organizers who learned their skills through apprenticeship, on the job training, or simply by trial and error. Today it requires at least four or five years of university study leading to a Bachelor of Science degree. More and more often engineers, especially those engaged in research, get an advanced master's or doctor's degree. Even those engineers who do not study for advanced degrees must keep up with changes in their profession and those related to it. All of this means that an engineer's education is never really finished so he must be willing to continue the learning process.
The word engineer is used in two senses. One, as just indicated, refers to the professional engineer who has a university degree and an education in mathematics, science, and one of the engineering specialties. Engineer, however, is also used to describe a person who operates or maintains an engine or machine. An excellent example of this is the locomotive engineer who operates a train on a railroad. Engineers in this sense are essentially highly-trained technicians rather than professional engineers.
The systems that engineers produce must be workable not only from a technical but also from an economic point of view. This means that engineers work with management and government officials who are cost-conscious so the engineer must accommodate his ideas to the financial realities of the particular project.
Today people are more conscious of the hidden or delayed hazard in products and processes. The automobile is a typical example. No one disputes its convenience but many are also aware of the air pollution it causes and the amount of energy it consumes. Engineers are working to solve these problems by designing devices that reduce pollution and improve fuel efficiency. The engineer, then, does not work in a scientific vacuum but must take into account the social consequences of his work.
Vocabulary
Apprenticeship
To keep up with
To be willing
To maintain
To operate a train
Highly-trained
Cost-conscious
Hazard
То dispute
То consume
Efficiency
навчання
бути добре обізнаними
бути готовим
підтримувати
керувати потягом
високоосвічений
чутливий до ціни
ризик
сумніватися
витрачати
продуктивність, ефективність
ENERGY
When the state or condition of a body is such that it can do work, the body is said to possess energy.
When we say that something possesses energy, we suggest that it is capable in some way of exerting a force on something else and performing work on it. When work is done on something, on the other hand, energy has been added to it. Energy is measured in the same units as those of work, the foot-pound and the joule.
Energy occurs in several forms. A familiar example is the energy a moving body possesses by virtue of its motion. Every moving object has the capacity to do work. By striking another object that is free to move, the moving object can exert a force and cause the second object to shift its position. It is not necessary that the moving object actually do work: и may keep on moving, or friction may slowly bring it to a stop. But while it is moving, it has the capacity tor doing work. It is this specific property that defines energy, since energy means the ability to do work, and so all moving things have energy by virtue of their motion.
This type of energy is called kinetic energy.
The statement that energy is the capacity something lias to do work is not restricted to kinetic energy but is perfectly general. Many objects possess energy because of their position. Consider a pile driver, a simple machine that lifts a heavy weight {'the hammer) and allows it to fall on the head of a pile, thereby driving the pile into the ground. When the hammer has been lifted to the top, it has only to be released to fall and do work on the pile. The capacity for doing work is present in the hammer as soon as it has been lifted, simply because of its position several feet above the ground. The actual work on the pile is done at the expense of kinetic energy gained during the hammer's fall, but the capacity for working is present before the fall starts. Energy of this sort, depending merely on the position of an object, is called potential energy.
Vocabulary
To exert a force
Foot-pound
Joule
By virtue of
Capacity
То define
A pile driver
Thereby
То lift to the top
At the expense of
приводитивдію
фут-фунт
джоуль
на основі, завдяки
функціональна здатність
визначати
машина, що забиває сваї
таким чином
підняти до найвищої точки
за рахунок
Machines
All students of technical specialties have to deal w'ith machines. Let’s define this simplest term. A machine is a device that uses force to accomplish something. More technically, it is a device that transmits and changes force or motion into work. This definition implies that a machine must have moving parts. A machine can be very simple, like a block and tackle to raise a heavy weight, or very complex, like a railroad locomotive or the mechanical systems used for industrial processes.
A machine receives input from an energy source and transforms it into output in the form of mechanical or electrical energy. Machines whose input is a natural source of energy are called prime movers. Natural sources of energy include wind, water, steam, and petroleum. Windmills and waterwheels are prime movers; so are the great turbines driven by water or steam that turn the generators that produce electricity; and so are internal combustion engines that use petroleum products as fuel. Electric motors are not prime movers, since an alternating current of electricity which supplies most electrical energy does not exist in nature.
The efficiency of a machine is the ratio of the output of work to the input of energy given in terms of a percentage. No machine is 100% efficient because of friction, the resistance to relative motion that is produced by two bodies moving in contact with each other. There are many other reasons why energy is never completely used; heat is lost into the atmosphere or the full force of a stream of water cannot be brought to bear on a wheel. Friction is a factor in all mechanical devices. In some cases, it is a factor which mechanical engineers try to overcome, but in others, such as braking devices, it is a factor that they try to use to advantage.
Vocabulary
Define
Force
Transmit
To accomplish
Tackle
Input
Output
Prime mover
Ratio
Friction
Resistance
Device
Bear
визначити
виконувати
передавати
сила
блок
сила,що застосовується,подача
вихідна сила,продуктивність
первинний двигун
коефіцієнт
тертя
опір
пристрій
опора