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For a long time the modern world is fascinated by the Egyptian culture and particularly from its monumental structures, so ask questions and make even studies to respond to them.
But the question that most researchers have set themselves so far is:
How did the Egyptians to move limestone boulders weighing about 2.5 tons, for the construction of the pyramids, for example the famous Pyramid of Cheope considered one of the seven wonders of the world still standing?
A team of Dutch physicists, led by Professor Daniel Bonn of the University of Amsterdam, may have found an answer.
To bring the stones to the site where stood the work, the workers were using large wooden sledges pulled onto the sand.
The secret is hidden just behind this process: normally during an operation of this kind, considering the load that weighed on sleds, dry sand would be piled in front, forming a bump ever higher that would made it costly and hindered the transport by labor; cunning led the Egyptians to wet the sand in front of the sled in order to reduce friction.
Physicists have reproduced in the laboratory in scale a tow, in a container containing sand, and measured with a special instrument called a rheometer the force required to drag the weight, both the compactness of the sand in relation to the quantity of water contained in it. The experiments have shown that the force required to pull the load decreases proportionally to the compactness of the sand: sands more compact and wet require less effort.
The drops of water between the grains of sand form very strong ties in fact – called capillary decks – which are slipped twice the load more easily, requiring half the workforce.
On a painting, it is clearly seen a row of workers pulling a statue in the desert, preceded by a man who washes the sand.
Beyond the historical value of the discovery, the results of the research could be used in the future to find easier ways to move granular materials such as asphalt, cement and coal, the transport of which requires, today, large energy expended.
