Classical mechanics is a field within physics that is concerned with the set of physical laws governing and describing the motions of bodies. It is enhanced by relativity, which relates to objects moving with high velocity approaching the speed of light. Classical mechanics is considered to be one of the oldest and largest subjects in science, engineering, and technology.
The concept of classical mechanics was created in the early 20th century to describe the system of mathematical physics devised by Sir Isaac Newton and other 17th century scientists. The first stage in the development of classical mechanics is referred to as Newtonian mechanics and is associated with the physical concepts and mathematical methods invented by Newton, Leibniz, and others. The majority of the content of classical mechanics was created in the 18th and 19th centuries and expands upon the work of Newton.
The term “classical mechanics” was coined to loosely label the set of equations that describe reality at scales where quantum (or really small phenomena) and relativistic (or very fast phenomena) are negligible. It evolved throughout the 18th and 19th centuries to describe optics, fluids, and heat as well as pressure, electricity, and magnetism. Classical mechanics accurately describes the behavior of what are deemed “normal” objects which are defined according to The Dynamic Chemistry E-textbook from UC Davis as “larger than a molecule and smaller than a planet.”
Some mathematical laws and principles which form the basis of classical mechanics include Newton’s First, Second, and Third Laws of Motion, Newton’s Law of Universal Gravitation, Law of Conservation of Energy, Law of Conservation of Momentum, and Bernoulli’s Principle. Newton’s First Law of Motion states that a body at rest will remain in rest and a body in motion will remain in motion unless it is acted upon by an outside force. Newton’s Second Law of Motion states that the net force acting on an object is equivalent to the mass of that object times its acceleration. Newton’s Third Law of Motion states that for every action there is an equal and opposite reaction. Newton’s Law of Universal Gravitation states that the pull of gravity between two objects will be in proportion to the masses of the objects and inversely proportionate to the square of the distance between their centers of mass.
The Law of Conservation of Energy holds that energy can neither be created nor destroyed and changes from one form to another instead, such as when mechanical energy transforms into heat energy. The Law of Conservation of Momentum states that in the absence of external forces such as friction, when objects collide, the total momentum before the collision is the same as the total momentum after the collision. Bernoulli’s Principle states that within a continuous stream of fluid flow, a fluid’s hydrostatic pressure will balance in contrast to its speed and elevation.
Classical mechanics has important applications in other scientific areas such as in astronomy with celestial mechanics, chemistry with regards to the dynamics of molecular collisions, geology with the growth of seismic waves generated by earthquakes through the Earth’s’ crust, and engineering with the equilibrium and stability of structures.