Above are three different pictures showing how some pulleys work!
Pulley: description:A pulley is a wheel with a grooved rim that turns on an axle. Pulleys changes the direction of the force. However, if you have a pulley system, it also increases the distance of the rope that you are using to move your object from one point to another. The more pulleys you have, the more rope you need and the less force you need to move an object.
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Pulley: origin
The creator of the pulley is believed to be Archimedes in the year 250 BC. This was the first reference of the modern day pulley that we know. Before vines were thrown over the limbs of trees to rise water and protect food. This is the older use. Going further in time to around the 17-1800's pulleys were used to trap deer and other animals for food and clothing. Hunters use the same kind of pulleys to catch bears, deer, owls, and other large birds for sport. Pulleys were also used for travel. For people going to explore, immigrate, and sell their items to other people they would use multiple pulleys to raise their sails, which would catch the wind.
Pulley: How they operate
The pulley is attached to a fixed pulley that holds the pulley steady. When you pull the rope or cable attached to the shaft or axle, the wheel turns. Pulling the rope attached to the shaft or axle on the pulley changes the direction in which the force is applied. When using pulleys you must apply enough force to overcome the mass of the load and any friction in the pulley system. The pulley system uses a block and tackle that's used to haul and lift heavy objects
A fixed pulley allows you to take advantage of the downward pull of the weight to move a load upward. A fixed pulley changes the direction of the force you apply on the object/pulley, however it DOES NOT reduce the force you need to lift the load/object. A movable pulley increases the distance in which the object is moving in.
A fixed pulley allows you to take advantage of the downward pull of the weight to move a load upward. A fixed pulley changes the direction of the force you apply on the object/pulley, however it DOES NOT reduce the force you need to lift the load/object. A movable pulley increases the distance in which the object is moving in.
Sources:
McDougal Littell Science: Motion and Forces by McDougal Littell
Machines Make It Move by Stephen M. Tomecek
http://en.wikipedia.org/wiki/Block_and_tackle
http://www.wpclipart.com/tools/miscellaneous/pulley/pulley_1.png.html
http://visual.merriam-webster.com/science/physics-mechanics/double-pulley-system.php
Flagpole picture
Rock Climbing Wall
McDougal Littell Science: Motion and Forces by McDougal Littell
Machines Make It Move by Stephen M. Tomecek
http://en.wikipedia.org/wiki/Block_and_tackle
http://www.wpclipart.com/tools/miscellaneous/pulley/pulley_1.png.html
http://visual.merriam-webster.com/science/physics-mechanics/double-pulley-system.php
Flagpole picture
Rock Climbing Wall
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