Physics and Technology – Physics – Mechanics
Mechanics is the oldest subject area in physics. Even early humans accomplished challenging tasks using levers and simple tools during the Stone Age. The ancient Greeks turned the development of machines into an art, the mechanike techne.
The Romans derived the word machina from this Greek term, and thus modern scientists began using the terms “mechanics” and “technology.”
Earth Science: Physics – Rest and Motion
The names of Johannes Kepler, Galileo Galilei, and Isaac Newton represent a time of development and revolutionary science emerging from a collection of inventions and experiences: the science of motion and its causes.
One of the most important realizations in mechanics is that each body has its own center of gravity. It does not matter if the body is a planet, a human, or a crystal. Its movement through time and space can be described as if the entire mass was concentrated in this one center of gravity (as long as the air resistance is ignored).
Grasping this abstract idea played a major role in advancing human intellect. Because of it, scientists were able to study motion by itself and to transfer findings to any applicable example.
Velocity and acceleration
The study of an object in motion is called kinematics (from the Greek word kinein: “to move”) and is a subject area in mechanics. One of the most important laws of kinematics states that velocity (v) is the quotient of the distance traveled (s) and the travel time (t): v = s/t. Its unit is miles per second (km/s).
In order to calculate the acceleration (a), the difference in velocity is divided by the travel time: a = v/t. This calculation gets more complicated when the value and direction of the kinematic quantities change during the process that is being investigated. Certain mathematical methods are required: differential and integral calculus.
These methods were eventually developed by scholars such as the Englishman Isaac Newton and the German Gottfried Wilhelm Leibniz.
Impact and momentum
The mathematical description of the planetary orbit of a cannon ball was a tremendous success of mechanics that gave it credence as a science. However, the causes of motion were described by physicists. This is how the concept of force was developed. An object, such as a ball, is accelerated by a greater force the smaller the mass of the object. Let us consider the product of mass and velocity: momentum.
Every impact changes the momentum exactly by the degree of the force acting on the object. Momentum also has a law of conservation of momentum, similar to the law of conservation of energy. A few mathematical conversions produce another conserved quantity for rotating objects, the angular momentum.
The laws of conservation are an important tool that is used to formulate and solve equations for every particle collision, every pirouette on ice, and so on, without having to consider the details of these processes.