Defying Gravity: The Archimedes Screw

 

Who was Archimedes?

 

Archimedes was a Greek mathematician, physician, inventor and engineer, born in Syracuse, Sicily, in 287BC. He was the son of an astronomer and mathematician named Phidias.

 

In the third century BC, Syracuse was a hub of commerce, art and science. Archimedes developed a natural curiosity and affinity for problem solving. He travelled to Egypt to study in Alexandria before returning to Syracuse, where he dedicated his life to research and experimentation across multiple fields.

 

 

The ‘Eureka!’ Moment

 

Archimedes was summoned by King Hiero to help him investigate whether he had been cheated by a goldsmith. The king had given a goldsmith the exact amount of gold needed to make his crown but the king suspected that he had been cheated and only some of the gold was used and combined with silver. The king asked Archimedes to solve the problem without causing any damage to the crown.

 

One day when taking a bath, Archimedes noticed that the water level rose as he eased himself into the water. He suddenly realised that a body immersed in fluid loses weight equal to the weight of the amount of fluid it displaces. This discovery excited him so much that he jumped out of the bath tub and ran through the streets naked shouting ‘Eureka!’, which comes from the ancient Greek meaning ‘I found it!’

This realisation meant the he could solve the King’s problem as he was able to measure the crowns density.

 

Pure gold is very dense while silver is less dense. So, if there was silver in the crown it would be less dense than if it were made of pure gold. The story says that when Archimedes tested this theory in front of the King by submerging the crown in water, he found that he had indeed been cheated by the goldsmith. This method of calculating the way in which an object displaces water to measure volume is called the ‘Archimedes Principle’.

 

 

The Archimedes Screw

 

Historians believe Archimedes invented the hydraulic screw which has come to be known as the Archimedes Screw. A famous story recounts how King Hiero was unable to empty rainwater from the hull of one of his favourite ships and so he called upon Archimedes for his assistance.

 

He invented a system whereby water could defy gravity and be carried up and out of the boat. This system featured a hollow tube containing a spiral that could be turned by a handle at one end.

When inclined at an angle of 45 degrees with its lower end placed in a body of water, the rotation of the device causes the water to rise in the hollow tube.

His Inventions

 

Archimedes is responsible for several of the simple machines we still use today including the pulley, the fulcrum and the lever. He invented a lot of these devices whilst he was working to defend the city of Syracuse during war.

 -Archimedes

 

 

Two other famous machines attributed to him are the catapult and the mirror system for focusing sun rays on invader’s boats and igniting them.

 

LER 2824 STEM – Simple Machines Activity Set

 

 

Archimedes’ Legacy

 

Despite being invented over 2000 years ago, the Archimedes Screw is still widely used today. From pumping water into turbines, creating green energy in Yorkshire or providing crop irrigation for farmers in the Nile Delta in Egypt!

 

 

Try it at home

 

Can you make water move uphill with your own Archimedes Screw experiment?

 

What you will need:

  • Jumbo Archimedes Screw
  • A Bowl
  • Cereal or small sweets

Problem:

You have gathered some rocks at the bottom of a hill. You want to move the rocks to the top of the hill, but they are too heavy. How can you move the rocks using an Archimedes screw?

 

  1. Place your “rocks” (Cereal or small sweets) in a bowl. Place one end of the Archimedes screw in the bowl and then tilt it to form a 45-degree angle
  2. Start turning the handle. Observe what happens to your “rocks”. Can you get any of the rocks to the top of the screw if you keep turning the handle?
  3. Can you move the objects faster? Can you get all of the objects from the bowl to the top of the screw?

 

 

 

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Sources:

http://archimedespalimpsest.org/about/history/archimedes.php

http://www.softschools.com/inventions/history/archimedes_screw_history/14/

http://www.bbc.co.uk/history/historic_figures/archimedes.shtml

https://www.youtube.com/watch?v=ijj58xD5fDI

https://www.britannica.com/technology/Archimedes-screw