Earth Science: Physics – Mechanics – of Apples and Planets
Prehistoric people already knew that objects have a certain weight. The novel idea is that the weight of, for example, a milk bag is actually the reciprocal attraction between the milk and the Earth.
Mass is not only a factor in Newton’s principle of action. It is also the critical quantity of gravitational force FG, also referred to as gravity or gravitational attraction. A reciprocal attraction of two masses only depends on the product of their masses and the distance r between the two: FG = G x m^1 x m^2/ r^2.
The constant of gravitation G is a quantity that remains a mysterious constant of nature. Its value is always the same in the entire universe and at all times, just like the electrical charge of an electron. To date, nobody knows why it is always the same.
Liquid mechanics
Archimedes’ discovery of buoyant force is a story that is just as fascinating as the .legend about Isaac Newton’s apple (see milestones): While he was bathing he discovered that a crown, which he was com- missioned to check for its gold content, became lighter once he put it in the water. He was so excited about his finding that he ran naked through town and shouted “Eureka” (“I found it!”).
Ever since, the mechanics of liquids and gases have become an important scientific discipline. Research areas include the investigation of the air resistance of flying objects or vehicles (known from the cW-value). Scientists of this discipline also investigate the behavior of liquids in pipelines as well as oceans and the atmosphere.
This subject area is called hydromechanics. It is not a basic science but mathematically very challenging. This is why the largest and fastest (for its time) computer in the world was constructed in 2002 for the purpose of hydrodynamic calculations on climate. This Japanese computer was called Earth Simulator.
Mechanics: an outdated discipline?
Mechanics in the classical sense of Galilei and Newton’s work has not been pursued as a novel research area for centuries. New discoveries are unlikely. More- over, some of the basic theories of classical mechanics were negated by Albert Einstein’s theory of relativity and quantum mechanics, which was developed only shortly after. And even today’s scope of mechanics has been questioned by the new chaos theory.
Many problems cannot be solved or their solutions are “chaotic.” Given these doubts, is mechanics still a relevant discipline? Absolutely. The theory of relativity only needs to be considered for extremely exceptional velocities and quantum mechanics differs from the principles of classical mechanics only when considering submicroscopic elementary particles.
The original laws of (hydro-) mechanics apply to everyone who wants to build high-rises, send satellites into space, or build wind turbines to use the power of wind. Today’s civilization depends on technology that is based on the art of engineering and advanced knowledge of mechanics—for throughout the course of history, mechanics has been the basis for new inventions.
NEWTON’S APPLE
Legend has it that Isaac Newton, while resting under a tree, observed how an apple fell from a branch to the ground. He was truck by the revolutionary idea that the apple was drawn to the Earth by the same gravitational force that existed between the planets and the sun.
Thus the classic theory of gravitational force was born. Newton recognized the mass of an object (the “heavy” as he called it) as a source of the ever present force of gravity