LIFTING UP LOWERING DOWN How do you move people animals and materials to different heights and down again safely and quickly Ancient humans made ladders carved handholds and built steep stairways into rock walls An elevator would have been helpful 4
The Sinagua people built cliff homes in the13th and 14th centuries where Arizona is today 5
No one knows when early engineers first tackled this challenge Sometime after the wheel was invented they discovered the pulley This well uses a type of pulley fixed
A pulley is a simple machine that uses a long pulling rope with a load attached on one end The other end is threaded along a grooved wheel The wheel changes the direction of the pull Moveable pulley Fixed pulley System of two pulleys
