A lever is basically just a long stick that you push or pull against a fulcrum to lift something, pry something open, or generally exert a large force on the other end. While levers help us move heavy things, they can also help us move things quickly. The earliest levers developed naturally inside animals' bodies. Examples of levers in nature can be found in almost all animals with joints, where knees and elbows act like fulcrums and arms and legs act as the levers themselves. Other intelligent animals have figured out the use of levers by using sticks and stones to pry open all sorts of fruits, plants and even animals with shells. Humans have being using levers for very long, using them like other animals at first but progressively employing them in more complex tasks like weaponry and construction.
Levers work by allowing you to do a lot of easy work instead of a little bit of hard work by using the mechanical advantage introduced by the lever. While you may be unable to raise a heavy object by a certain distance, a lever would enable you to do so easily, by pushing it for 5 times the same distance, for example. A good way to think about this is to consider that the same amount of work is done, only it is now considerably spread out. Pushing or pulling a lever for twice a distance is likely to make lifting or opening an object require half the force; pushing or pulling a lever for three times the distance will make the job require one third of the strength, and so on.
Some modern examples of levers are using a hammer to pull out a nail, using a bottle-opener to open a beer bottle, using a nut cracker to crack nuts, using a nail clipper to cut your nails, or bluntly using a crowbar to pry open a door.
Some modern examples of levers are using a hammer to pull out a nail, using a bottle-opener to open a beer bottle, using a nut cracker to crack nuts, using a nail clipper to cut your nails, or bluntly using a crowbar to pry open a door.
Can you identify the fulcrum in these two examples?