Simple Machines

The first pieces of technology involved by primitive humans were simple machines that helped them solve physical problems . The simplest and most effective - the wedge , the lever , and the pulley - could multiply and change the direction of force . They are still in daily use in the 21st century .

LEVER

People have always wanted to do things that needed more than normal human strength - move heavy stones, cut wood, or kill animals for food or in self - defence so they invented machines to increase the force they could exert. The simplest machines for multiplying force are the wedge, the lever, and the pulley. The wheel (see pp.20-21) was also helpful for moving things over smooth ground.

ARCHIMEDES SCREW

This type of pump is said to have been devised by Archimedes during the 3rd century BCE . It has certainly been used for thousands of years for irrigation, and is still used today for pumping sewage and similar sludge. It is a simple helix-like a wood screw but of constant diameter- inside a close-fitting tube. As the handle is turned the liquid is pulled up the tube, each bucketful trapped in a compartment that seems to move steadily upwards.