Levers: discription
A lever is a rigid bar that rotates around a fixed point called a fulcrum. By putting effort on the opposite end of the load it moves up, the farther away you put the effort the easier it it to move the load. The founder of the lever is unknown but it was first used in ancient Egypt. Some examples of levers are scissors, hammers, tweezers, seesaws, and crowbars. Levers make work easier by increasing distance and decreasing force.
Diagrams:
levers: Historical use
There was a lever invented in Egypt called a Shaduf. A Shaduf is hand-operated and was used for gathering water from the irrigation canals that were used for farming. A pole is balanced on an upright structure, which is the fulcrum. There is a weight attached to one side and that acts as the effort. On the other side there is a bucket which is the load. On the side of the pole their is a rope that when it's pulled it causes the bucket to dip into the irrigation canals throughout the land. When it is released it brings the bucket back up.
When the lever was first used and who invented it:
The First class, Second class, and Third class lever was invented by a anonymous person. The lever was first described/used by a mathematician named Archimedes.
These are a few pictures of real life levers:
These are a few pictures of real life levers:
Here are two Modern day Examples
Sources
McDougal Littell Science: Motion and Forces by McDougal Littell
Machines Make It Move by Stephen M. Tomecek
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http://www.weebly.com/uploads/3/3/9/2/3392380/368842223.jpg?287
http://www.weebly.com/uploads/3/3/9/2/3392380/4039846.png?250
http://www.weebly.com/uploads/3/3/9/2/3392380/635237833.jpg
http://www.weebly.com/uploads/3/3/9/2/3392380/8717122_orig.png
http://www.kidsgen.com/school_projects/images/how-a-lever-works.jpg
http://media-cdn.tripadvisor.com/media/photo-s/01/2e/15/e8/the-drawbridge.jpg
http://3.bp.blogspot.com/-kEZeGpPm-fM/UKG-HKKhmhI/AAAAAAAAKP0/NjNIG7pR-_4/s640/Photo+Nov+12%252C+1+54+45+PM.JPG
Credits: Moritz S, Abby M, Bronya S
McDougal Littell Science: Motion and Forces by McDougal Littell
Machines Make It Move by Stephen M. Tomecek
http://www.weebly.com/uploads/3/3/9/2/3392380/4088548.png?340
http://www.weebly.com/uploads/3/3/9/2/3392380/368842223.jpg?287
http://www.weebly.com/uploads/3/3/9/2/3392380/4039846.png?250
http://www.weebly.com/uploads/3/3/9/2/3392380/635237833.jpg
http://www.weebly.com/uploads/3/3/9/2/3392380/8717122_orig.png
http://www.kidsgen.com/school_projects/images/how-a-lever-works.jpg
http://media-cdn.tripadvisor.com/media/photo-s/01/2e/15/e8/the-drawbridge.jpg
http://3.bp.blogspot.com/-kEZeGpPm-fM/UKG-HKKhmhI/AAAAAAAAKP0/NjNIG7pR-_4/s640/Photo+Nov+12%252C+1+54+45+PM.JPG
Credits: Moritz S, Abby M, Bronya S