Term
|
Definition
| a lever is an object that is used with a pivot point, or "fulcrum" to multiply force applied to another object. Levers are often long and skinny and made of stiff material, such as hard woods or steel. Levers are one of the six simple machines. |
|
|
Term
|
Definition
| Levers can be man-made, but many levers are natural, such as your arm and jaw. Noone is really sure who invented the first mechanical lever. Mechanical Levers have been used by humans as far back as the Stone Age. Archimedes provided early writings about levers that were dated from the third century B.c. "Give me the place to stand, and I shall move the Earth" is a remark of Archimedes who was the first to mathematically describe how levers multiply force.In ancient Egypt,builders used the lever to move and lift up obelisks, a four sided shape that has a pyramid-like top, weighting more than 100 tons. A Shadoof, a type of lever that was used in Egypt to lift water from a well or river for irrigation, a shadoof is a pole with a weight on one end. |
|
|
Term
|
Definition
| A lever can be used to give of a large force over a distance at one end by giving off only a small force over a greater distance at the other. A lever lets people do work using less strength. A lever usually is used to move or lift objects, but is sometimes used to push against objects, but not actually move them. |
|
|
Term
| How does the lever get its power? |
|
Definition
| A lever gets it power from outside forces acting on it. The force applied to one end of the lever is transferred to the other end of the lever. A mechanical advantage is the real power of levers. The lever allows less effort to be used when moving an object, and the object will move a shorter distance than the person trying to move it. For example, A crwobar can be used to pry up a board because it applies a lot of force over a short distance when the person using the crowbar uses much less force. |
|
|
Term
|
Definition
| The lever has two important parts, the lever itself and the fulcrum, the support or point of rest on which a lever turns when moving a body, The placement of the fulcrum determines how far the levered object will move, and how much force is required to move it. If a weight was resting ona lever a person could lift the weight by pressing on the lever on the other side. The farther away the fulcrum that person pressed, the less force that person would need to apply. In order to lift tje weight the same distance, the force would have to be applied over a longer distance. In science, Work is defined as moving an object. Work is made easier with a lever. If you are moving the lever further, then you don't have to oush as hard to do the same amount of work. |
|
|
Term
|
Definition
| There are actually three types of levers, First class levers, second class levers, and third class levers. An example of a first class lever is a see-saw. In a first class lever the fulcrum is located between teh force pushing down or the input force (the person going down) and the output force (the persib going up). |
|
|
Term
|
Definition
| A wheel barrow is an example of a second-class lever, where the resistance is located between the effort and the fulcrum. The input force would be the handles. The fulcrum is located on the axle of the front wheel. |
|
|
Term
|
Definition
| An example of third-class lever is a baseball bat where the lever effort is between the fulcrum and the resistanc. In this example, the effort is exerted by swinging the bar at the handle. The heavier part of the bat is teh resistance. In this case, the force at the end of the bat is actually reduced, but the speed is increases. The end of the ba moves faster than the grip where the force is applied, giving momentum, causing it to strike the ball harder. |
|
|
Term
| How has it changed the world? |
|
Definition
| The lever has changed the way we work by helping us to do more work with fewer resources. It played an important role in developing agrculture and also played a important role in building shelters and other types of buildings. |
|
|
