# Simple Machines

Topics: Pulley, Simple machine, Torque Pages: 2 (861 words) Published: December 17, 2006
Many simple machines have been created even since the early times. According to Ron Kurtus from his website article, "Simple Machines", the ancient Egyptians used levers to lift stones to build their pyramids and ramps to raise them to the top. Also he states that in Roman times, stones were tossed at enemies using catapults. The catapults used levers to fling the stones, and pulleys to pull down the arm of the catapult. The purpose of all of these simple machines is to lessen the amount of work or effort that you must put into a job. The pulley, inclined plane, gear, spring, and lever are good examples of simple machines. In the following paragraphs I will give more information about three of these, the pulley, inclined plane, and the gear. The whole concept the pulley is based on is changing the direction of the force being applied. Just using a wheel to allow a rope to be pulled in a different direction can be much easier on someone. A pull downward on a rope to lift something is often easier than bending over and picking the load up yourself. Single pulleys are used in many complex machines where the direction of movement must be changed. One of the complex machines that pulleys are used in is the elevator. The elevator car is lowered or raised by large cables and a pulley at the top. The end of the cable has counterweights that balance the weight of the car and passengers. The electric motor turns the pulley so the car moves up and down. Even though you may not notice them, pulleys are everywhere such as on bikes, cable trams, ski lifts, and more. Pulleys can also be connected to be more powerful. For instance, if you connect two pulleys together, the rope is connected around both pulley wheels. This allows more weight to be lifted since the force raising the weight is double the effort pulling the rope. Utilizing this, you can setup a block and tackle system. This is a bunch of pulleys that are connected to raise substantial loads. The amount of pulleys you...