Simple machines were created to make work easier for people. They are the basis of more complex machines, such as cars. The six simple machines are wheel and axle, lever, pulley, inclined plane, wedge, and screw. Archimedes is responsible for his work in creating the lever, pulley, and screw. Simple machines began thousands of years ago and were employed throughout various civilizations to accomplish amazing tasks. The everyday items we use include many simple machines or groups of simple machines, called compound machines.
Wheels and Axles
The wheel and axle can be found in cars, obviously working to make the body of the car propel forward or backward. Rice University states that the wheel and axle have a short movement of the wheel with a more powerful movement at the axle. A steering wheel relies on the work of the wheels and axles in a car. The size of the steering wheel and whether or not there is power steering can affect the force needed to control the wheels and axles in a car.
For a lesson plan using wheels and axles, have a look at The Ohio State University's GK-12 Program.
A lever is a simple machine that can do three things: change the direction of applied force, change the distance and speed of movement produced by applied force, and change the effective strength of the applied force, as stated by Murray State University. A plank would be balanced on a fulcrum. An example of a lever would be a see-saw. You can find levers in a car with the gear shift.
The University of Houston describes a pulley as a simple machine made with a wheel and rope. A rope will fit in the groves of a wheel. If you attach a heavy load to one side of the rope and pull with the other, it becomes easier to move as the rope moves the wheel. Pulleys are most useful when moving heavy loads. Pulleys are used in sailboat ropes, window blinds, and more.
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Whether you knew or not, a screw is a simple machine. Science Encyclopedia defines a screw as an inclined plane that has been wrapped around a central axis. Screws have several jobs including to hold things together and to apply force to other objects. When screws are applying force, some examples would be a vice, a corkscrew, or a press. You can also make your own screw by rolling up a piece of paper and wrapping it around a pencil. You can find screws on lightbulbs, faucet parts, and bottle caps. Screws can also be found in cars as they hold parts together in all places inside them.
The Archimedes screw, invented in 250 BC, helps irrigate water or move grain and other liquids from one place to another. This simple machine is still used today in some parts of the world.
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An inclined plane is a simple machine that helps us to raise an object with less effort than to lift it upwards. An example of an inclined plane would be a ramp leading up to a moving truck or the slides at a park, according to Astrophysics Science Project Integrating Research and Education.
Dartmouth University shows us that famous scientist, Galileo, conducted experiments with inclined planes to explain the natural motion of objects. Because 17th-century clocks were not fitted to count the smallest amounts of time, Galileo used a simple machine, an inclined plane, to slow down the natural motion of objects to record time data.
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A wedge is a triangular object which is placed between two objects to hold them in place or to move one relative to the other, as explained by the University of Nebraska. Examples of wedges are door stoppers, an axe to split wood, or a can opener.
An article at the Wilson School District website says wedges are used to magnify force. The oldest human tool is a chisel, which is a type of wedge. A wedge is used to move one object into another.
Up until this point, we have talked about simple machines. When we group two or more simple machines together, it becomes a compound machine. When we combine a lever, wheels and axles, and screws together, they make a compound machine, like a car. Cars have hundreds of simple machines inside them to put them in motion. The University of Virginia also shows us that a bicycle (wheel and axle, screw, and lever), an axe (wedge and lever), and a piano (two or more levers) are compound machines.
CK-12 tells us that compound machines, while useful, have more friction to overcome thus making them not as efficient as the simple machines that they are created with. In the case of a car engine, a large amount of simple machines working together cause friction and heat. Oil or grease is needed to keep all the parts working properly and prevent friction from destroying them. However, compound machines have a technical advantage over simple machines. The more simple machines there are, the greater the mechanical advantage the compound machine will have.
Resources for Parents and Teachers
If you would like to teach your children or students about simple machines, and how numerous simple machines together create compound machines, please have a look at the resources below for fun and interesting lesson plans:
WKAR Public Media from Michigan State University has some great information at Wheels and axles.
Idaho Public Television offers facts about simple machines at Facts about simple machines.
National Agriculture in the Classroom talks about simple machines at Six kinds do it all.
Math and Science Nucleus discusses more about simple machines at Exploring simple machines.
PBS Kids offers a simple machine challenge at Simple machines challenge.
South Haven Public Schools has helpful information on simple machines at Simple machines guide.