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Engineering is concerned with the design of a solution to a practical problem. A scientist may ask "why?" and proceed to research the answer to the question. By contrast, engineers want to know how to solve a problem, and how to implement that solution.
In other words, scientists investigate phenomena, whereas engineers create solutions to problems or improve upon existing solutions. However, in the course of their work, scientists may have to complete engineering tasks (such as: designing experimental apparatus, or building prototypes), while engineers often have to do research.
However, engineering research has a different character to scientific research. Firstly, it often deals with areas where the basic physics and/or chemistry are well understood, but the problems are too complex to solve exactly. The purpose of engineering research is then to find approximations to the solution that can be solved. Examples are the use of numerical approximations to the Navier-Stokes equations to solve aerodynamic flow over an aircraft, or the use of Miner's rule to calculate fatigue damage to an engineering structure. Secondly, it employs many semi-empirical methods that are foreign to pure scientific research, for example the method of parameter variation.
In general, it can be stated that a scientist builds in order to learn, but an engineer learns in order to build.
As an illustrative example, on November 21, 1877, Thomas A. Edison developed the phonograph — a remarkable feat of engineering. Then, he directed his assistant (the technologist) to improve the device further by removing harmonics from the sound output.
"An engineer is someone who can do for fifty cents what any fool can do for a dollar."
The crucial and unique task of the engineer is to identify, understand, and integrate the constraints on a design in order to produce a successful result. It is usually not enough to build a technically successful product; it must also meet further requirements. Constraints may include available resources, physical or technical limitations, flexibility for future modifications and additions, and other factors, such as requirements for cost, manufacturability, and serviceability. By understanding the constraints, engineers deduce specifications for the limits within which a viable object or system may be produced and operated.
Engineers use their knowledge of science and mathematics, and appropriate experience, to find suitable solutions to a problem. Creating an appropriate mathematical model of a problem allows them to analyze it (perhaps, but exceptionally, definitively), and to test potential solutions. Usually multiple reasonable solutions exist, so engineers must evaluate the different design choices on their merits and choose the solution that best meets their requirements. Compromises are at the heart of all engineering designs; the "best" design is that which meets as many of the requirements as possible.
Engineers typically attempt to predict how well their designs will perform to their specifications prior to full-scale production. They use, among other things: prototypePrototypes or prototypical instances combine the most representative attributes of a category. They are the best examples among the members of a category and serve as benchmarks against which the surrounding "poorer" instances are categorized (see Prototys, scale modelA scale model is a representation or copy of an object that is larger or smaller than the actual size of the object being represented. Very often the scale model is smaller than the original and used as a guide to making the object in full size. Scale mods, simulationA simulation is an imitation of some real device or state of affairs. Simulation attempts to represent certain features of the behavior of a physical or abstract system by the behavior of another system. Simulation is used in many contexts, including thes, destructive testIn destructive testing tests are carried out to the specimen’s failure. These tests are generally much easier to carry out, yield more information, and are easier to interpret than nondestructive testing. Testing of an object is often done in view of futus, nondestructive testingIn nondestructive testing tests are carried out in such a way as to not disturb the specimen’s structural or surface integrity. This type of testing is valuable because the specimen is not destroyed, however, these techniques generally require greater ope, and stress testStress testing General definition Cardiac Stress Test is used to identify possible problems with the heart.s. Testing ensures that products will perform as expected. Engineers as professionals take seriously their responsibility to produce designs that will perform as expected and will not cause unintended harm to the public at large. Engineers typically include a factor of safetyFactor of safety (FoS), also known as Safety Factor is a multiplier applied to the calculated maximum load ( force, torque, bending moment or a combination) to which a component or assembly will be subjected. Thus, by effectively "overengineering" the des in their designs to reduce the risk of unexpected failure. However, the larger the safety factor, the less efficient the design will be.