# Introductory Concepts in Mechanics

## The Measure of Things - History

### Antique

In our present civilization, measurement processes are quite complex in order to meet the needs of science and technology.

In ancient times man has used simple processes sufficient for his primitive technique. But when did you start measuring? It probably started when I wasn't even talking yet, because could measure or compare one fish with another, which is the largest or the smallest. It would also be known to you that a certain amount of food satiated your hunger. Obviously, they were intuitive ways of measuring.

From the moment man began to live in groups and as these clusters grew, the need to measure increased even more. The ways in which they measured magnitudes were quite simple: they used parts of their own bodies, such as the length of the foot, the width of the hand or the thickness of the finger, the span and the stride. They also used a stick or a stick.

With the emergence of the first civilizations, such processes no longer satisfied the needs of men, for they knew note the differences of those parts for each individual. Shipbuilding, division of land, and trade with other peoples required standard measures that were the same everywhere. Thus a Babylonian cloth merchant could sell his wares in Jerusalem, using a standard stick approximately the size of the one adopted there.

The ancient peoples - the Egyptians, the Babylonians, the Assyrians, the Chinese, the Persians, and the Greeks - had different length patterns. The unit of length of the Babylonians was the finger (approximately 16mm). They also used the ulna, which was 30 fingers. Foot and inch were, for these people, generally the standard units.

Interestingly, according to LA Sanches, the Egyptians had a strange measure called the "pyramidal inch" found in the great Cheops pyramid near the Nile, built in 3 or 4,000 BC. When studied, they concluded that the diameter of the earth measures one and a half billion of these inches. Calculating the perimeter of the base of the pyramid is 365 242 inches, the result of which figures exactly express the number of days in the solar year (365,242 days).

Man also had to weigh, or rather compare, masses, for weight and mass are two different quantities, the first being a force resulting from the gravitational pull, as you'll see later in your physics course. Mass is the amount of matter in a body, or in more physical terms, the resistance it offers to an applied force. Weight may vary depending on conditions and mass is invariant at rest. In the early days man compared the mass of two bodies by balancing them on each hand. Until the first comparison machine came up: a stick suspended in the middle by a rope. The objects were hung at their ends, and if there was balance, that is, if the stick was horizontal, they had the same mass.