Mechanical Engineering
Concisely, mechanical engineering applies the principles of physics to design mechanical systems. Of course, it is much more than that: our definition is very simplistic. Mechanical engineers need to have an intimate understanding of the common engineering principles and concepts, such as mechanics, fluid dynamics and thermodynamics.
Using motor mechanics as an example, it is the duty of the mechanical engineering team to design the engine of a motorcar. An engine is a very intricate piece of machinery, built to very fine tolerances and expected to operate reliable for hundreds of thousands of kilometres with only periodic and very basic servicing requirements.
Engine designs are never clean-sheet designs. Established theories are followed and new solutions explored, but every piston engine has the same broad characteristics and operate according to the principles and constraints set by the basics of piston engine design and the process of fuel combustion. There are always advances in the application of new materials and techniques, but the basic architecture is always recognisable.
Although most mechanical engineering principles can be simulated by computer and demonstrated in a virtual environment according to the laws of physics, a lot of sound engineering practices have come about by experimentation in areas that were very much a "black art", many years ago before current advances would have made such experiment unnecessary. Of course, the current advances would not have come about in the first place, had it not been for the experiments of visionary engineers that toiled away for hundreds of years to establish practices and principles we take for granted today!
The wheel is a sound example and, while it seems all too logical and simple, it was nevertheless a spectacular breakthrough when the design was first stumbled upon. In similar vein, the basics of the Otto Cycle, the Diesel combustion process, the Wankel engine and the MacPherson strut or Watts linkage were all once not so basic, hence these designs are named for the mechanical engineering visionaries that designed them and are used to this day, right down to their basic principles.