Earlier humans used wedges made of hard rocks and stones to hunt like spears , cut and trim trees, and carve stones. The concept of wedges is also used in jets and modern cars. You will notice that jets, fast cars, speed boats, and trains have pointed noses. That helps them cut through the air air acts as a resistance.
This feature of pointed noses cutting through air is known as aerodynamics. Skip to content Simple Machines. What is a machine?
Types of machines. The Inclined Plane. The Wedge. The Screw. The Lever. Some examples of wedges that are used for separating might be a shovel, a knife, an axe, a pick axe, a saw, a needle, scissors, or an ice pick. But wedges can also hold things together as in the case of a staple, push pins, tack, nail, doorstop, or a shim. The pulley is actually a version of a wheel and axle that is combined with a rope, chain or other cord to allow moving something up and down or back and forth.
The pulley can be combined with other pulleys to reduce the amount of work necessary to lift huge amounts of weight or to lower them down. It can also make moving something such as a flag up the pole convenient to do from the ground.
It changes the direction of the force necessary to do the work. I pull down on the rope, but the flag goes up. Pulleys are used in window blinds and drapery to move them up and down or back and forth. Pulleys are also used on ships to raise and lower sails, in industry to raise and lower heavy cargo, or on cranes for use in moving construction equipment.
Elevators also use pulleys to move the car up and down from floor to floor. The screw is really a twisted inclined plane. It allows movement from a lower position to a higher position but at the same time it moves it in a circle. That makes it take up less horizontal space.
A screw can also act to hold things together in some cases. Some examples of the uses of a screw are in a jar lid, a drill, a bolt, a light bulb, faucets, bottle caps and ball point pens. Circular stairways are also a form of a screw. Another use of the screw is in a device known as a screw pump. A huge screw shape is lowered into the water and by turning the screw the water is moved up the twisted shaft and lifted to where it is needed.
Screw pumps are often used in agricultural settings such as farms and for irrigation. A person can push against a brick wall until they sweat. But unless they moved the wall — even a tiny bit — they did no work. But at the same time, if you scoot the computer mouse even a part of an inch, you have done work.
Work in the scientific sense. Don't try to convince your parents or your teachers that you have done a lot of work by playing video games. Work can be measured.
It is measured by the amount of distance that a force moves an object. Sir Isaac Newton was a very famous scientist who had a wonderful understanding of the relationship between force and motion. For this reason, the measurement is known as a Newton. A wedge is two inclined planes back to back against each other. Wedges evolved on their own long before people. Sharp teeth are a kind of wedge that cuts through meat and vegetables when fish or crocodiles eat something.
People have been using wedges in Africa since the earliest Stone Age, about 2. These early wedges were stone hand-axes, and their sharp edges let people cut a hunk of meat off a gazelle to eat, or cut branches for firewood.
Probably people also used wooden wedges to split bigger pieces of wood into smaller pieces. The mechanical advantage you get from a wedge depends on how thick it is. A thin long wedge will be easier to drive in, but it will take longer to split something. Today we have many different uses for wedges. A plow is a kind of wedge. A knife is a kind of wedge, and a fork is made of four little wedges. Razors and scissors are wedges too. So are doorstops.
A nail is a kind of wedge, and so is the pointed nose of an airplane, that helps it cut through the air more efficiently. So what is a wedge? Did you find out what you wanted to know about simple machines? Due to the wedge's shape the tree stump breaks apart just like the object in the above image.
The axe, or wedge, helps make splitting apart the tree stump much easier that doing it by hand. There are two types of wedges: single and double. The examples above are both double wedges. A doorstopper and a chisel are examples of single wedges. Another example of a double wedge, much thinner than an axe, is a knife. All knives are wedges, as are nails, because of their ability to cut or split, and in the case of the nail, to hold something together.
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