- Education and Science
What Are 'Simple Machines'?
When you think of the word "machine" what do you envision? Maybe it's something with a computer, such as a robot, or a complex piece of metal and wires.
The Free Dictionary defines a machine as "A device consisting of fixed and moving parts that modifies mechanical energy and transmits it in a more useful form" or "A system or device for doing work."
But "simple machines" are exactly the opposite, in fact, many simple machines are made of one piece and have little to no moving parts.
Simple machines are tools that use one movement to complete work, they also increase the amount of work someone is able to do without exerting a lot of effort. Essentially, simple machines help people lift, push, move, divide and pull easier.
Types of Simple Machines
There are six types of simple machines: the lever, inclined plane, wheel and axle, screw, wedge, and the pulley.
- Levers are basically bars that rest on a supportand lift or move things. Basic examples of a lever are a crow bar, or the forked part of hammer that removes nails from wood.
- Inclined Planes are flat surfaces that connect a lower level to a higher level. A basic example of an inclined planes is a slide or ramp.
- Wheel and Axles is a more complex "simple machine" that involves a wheel and a rod that allows the wheel to freely turn. Think of any wheel (such as on a wheel barrow) for a basic example.
- Screws combine an inclined plane (the thread on the screw) and a lever wrapped around a pole (the head of the screw).
- Wedges use something with slanted sides (and sharp sides) to lift or split something apart. A crowbar is a good example of a wedge too.
- Pulleys use grooved wheels with ropes to lift or pull something in another direction. A basic example of a pulley is the the part of the flagpole that lifts the flag up and down. Although you can use one pulley by itself, when you use more pulleys it takes less and less effort to move things.
Think about it, did you use a simple machine today? Well, you probably walked (up or down) some stairs— that's a version of an inclined plane. Did you drive in a car today? That has a wheel and axle. Did you work in the garden with a shovel? That shovel is an example a wedge.
More About Levers
Remember when I said that simple machines have little to no moving parts, well levers have four major components: the bar, fulcrum, load and the effort.
Consider the playground favorite, the teeter totter (or seesaw). The "bar" is the the inclined plane, the "load" is the lower end (where someone is sitting), the "fulcrum" is center part of the teeter totter that balances the two ends, and the "effort" is the part of the teeter-totter that is up in the air, and needs to be pushed down in order to lift the "load" end up.
Levers are used for more than just playground fun though, they have been used in history by the ancient Egyptians for moving water from the Nile river to water crops, they are used every day in construction, and even in the wonderful device called the "vending machine".
More About Inclined Planes
A "plane" is a flat surface. But an "inclined plane" is a flat surface that connects a lower level with a higher level.
Imagine trying to get from the first story of a mall to the second story without an inclined plane. Unless you had some sort of superhuman strength, such as spiderman or superman, it'd be very hard to get upstairs without an inclined plane. In fact, your mall likely has several sorts of inclines planes in the form of stairs, ramps, escalators. Getting from a lower level to a higher level is difficult because of gravity, but when you use inclined planes you lessen the force of gravity.
Skateboarding on a flat surface can get you from point A to point B quickly, but inclined planes make skateboarding oh so much more fun! Inclined planes are also featured in many winter sports, such as skiing, the luge, and bobsled. Without the inclined plane, the sportsman would just stand, sit, or lie still.
More About Wheels and Axles
Wheels and axles are joined together in the center; when one part rotates, so does the other. In fact wheels and axles aren't all about vehicles, that same gizmo is inside the doorknob too.
The wheel dates as far back in history as Mesopotamia, more than 5500 years ago! And wheels were painted on ancient ruins, and even placed in the tomb of the famous King Tut.
Gears are a form of the wheel and axle, in that they are wheels with "teeth" on the outside. Gears always work in pairs. When one gear moves, it passes along the energy to the other gear, and moves that gear too.
Wheels and axles appear in things such as watches, bikes, rolling pins and more. Can you imagine a life without wheels? We wouldn't be able to get places as fast without them.
More About Screws
The screw is an inclined plane wrapped around a rod or shaft, which allow it to move in a circular motion pulling one thing toward another.
Everyone has seen a screw, it looks like a nail with a groove on it, but screws are used in more than just holding wood together. You’ll find screws on the ends of light bulbs, clamps, drills and more!
Stairways are also considered a type of screw, since the ramp wraps around and around, helping to elevate the person higher up or lower down.
More About Wedges
Wedges have one or two sloping slides, and end in a sharp point. Wedges can be used to lift or split an object, and can move or even stop something from moving too.
Remember that Swiss army knife pictured in the first article on simple machines? It’s main component— the knife— is an example of a wedge. When you want to cut an apple open you use a knife, not a spoon, that’s because the knife can best split things open. When you use a knife, you force the knife down and sideways to force the apple open.
Another example of a wedge is a door stop, it’s a type of ramp that stops the door from opening. An axe is also an example of a wedge because it splits the wood in two pieces.
More About Pulleys
Pulleys are grooved wheels with ropes that help lift, pull and lower heavy things (known as the “load”) with little effort. Pulleys aren’t relegated to flagpoles, you’ll find them in mini blinds, tow-trucks, ski hills, construction sites and more! You can even make pulleys without the wheel— just hang a rope over a tree branch. tie it to something heavy, and pull the rope at the other end. Actually, there are three basic types of pulleys:
- Fixed pulleys— joined at a point that doesn’t move
- Moveable pulleys— the pulley and the “load” (the thing you want to move) move together
- Compound pulleys— where fixed and moveable pulleys work together
So the next time you want to move something or travel somewhere, consider how simple machines make lives easier, and how thankful you should be for the easy things in life– simple machines. Instead of using your own muscle, see how simple machines can make your efforts easier.