Simple Machines

Simple Machine Facts

Simple Machines ['sim-pəl] [\mə-'shēns\]

A device with few or no moving parts.

Caveman, manly boy with weapon

Once upon a time a person needed to move something heavy. He or she picked up a long stick and stuck it under the edge of the heavy object and then pushed down on the other end of the stick. And the first simple machine was invented. Simple machines are just that. The simplest form of using one thing to accomplish something faster or better. A tool. They were the first ones created and we still use them today.

There are 6 basic simple machines; the lever, the wheel and axle, the inclined plane, the wedge, the pulley, and the screw. Several of these simple machines are related to each other. But, each has a specific purpose in the world of doing work.

But what is work? Work is the amount of energy necessary to move an object. The further you move it, the more work is required. Work is measured in joules.  More about that later. First let's look at each of the 6 simple machines in detail. 

The Lever


The lever is a long tool such as a pole or a rod put under an object to lift it. The lever is more efficient when combined with a fulcrum. The fulcrum is another object, perhaps a rock, used to brace under the long tool. This gives the long pole something to push down against. The location of the fulcrum helps determine how well the lever will perform work. The closer the fulcrum is to the object being lifted, the easier the person can lift the object. The longer the lever, the higher the object can be lifted. Do the math — it's really all in the distance between the object, the fulcrum and the lever.

Levers are all around us. Some examples of levers are: door handles, the claws of a hammer (for removing nails), crowbars, light switches, bottle openers and hinges.

Man using crowbar

The Wheel & Axle


The wheel has always been considered a major invention in the history of mankind. But it really would not work as well as it does had it not been for the axle. An axle is a rod or pole centered in the wheel that allows the wheel to turn around it. The wheel then spins in a balanced circle to be used as transportation on a bike or to turn the hands of a clock. Gears are a form of the wheel and axle.

Wheels are found where things turn in a circle such as an electric fan, a motor, a revolving door, a merry go round, and any wheel — on the car, on your skateboard, or on a bicycle.

Risk taker merry go round park fun

The Inclined Plane

Ramp skating yellow and gray color
Excited boy with skateboard sitting on ramp

The inclined plane is simply a ramp. One end is higher than the opposite end. This allows things to go from a low point to a higher point. Or vice versa. It takes the same amount of work, but less force, to move an object up a ramp than to move it vertically. Gravity makes it easier to move an object down a ramp than up that ramp.

Ramps are used in skateboard parks, wheelchair ramps and to get heavy equipment in and out of the back of trucks. But a modified version of a ramp is also found in stairs, escalators, ladders, walking paths, even chutes used for dropping your mail into the mailbox.

The Wedge

A deck of stacked logs and an axe
close up of a pushpin on white background

Some people might see the wedge as just an inclined plane, although it is actually two inclined planes. However, the use of a wedge is actually different in nature. The wedge is used to separate an object apart. This is needed to cut, tear or break something in two. A wedge can also be used to keep things together or secure things from movement.

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

Sailing yacht rigging equipment

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.

Rigging and ropes on an old sailing ship to sail in summer

The Screw

Close up of screws

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.

Measuring Work

Kids pushing barrel of straw

Work is the amount of energy necessary to move an object. Work is only done when a force acts on an object to move it some distance from its starting point. 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. At the same time, if you scoot the computer mouse even a part of an inch, you have done work in the scientific sense. But don't try to convince your parents or your teachers that you have done a lot of work by playing video games!

vintage domestic spring scale isolated on white

Work can be measured. It is measured by the amount of distance that a certain 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 of the force applied to an object is known as a Newton. The amount of work is calculated by multiplying this force by the distance the object moves. The joule is used to measure work in terms of "newtons per meter." The joule, where the newton is the force and the meter is the distance, is the standard unit for measuring work.  If it takes 1 newton of force to move an object 1 meter, then that is equivalent to one joule of work. A force of 10 newtons that moves an object 3 meters does 30 joules of work.  

There are special tools for measuring the force necessary to move an object. These are known as force meters. They use a spring and a hook to determine how much pull is required to slide an object up an inclined plane and quite simple to use.

Compound Machines

Simple machines can be combined together to form compound machines. Many of our everyday tools and the objects we use are really compound machine. Scissors are a good example. The edge of the blades are wedges. But the blades are combined with a lever to make the two blades come together to cut.

lawn mower in the garden

A lawnmower combines wedges (the blades) with a wheel and axle that spins the blades in a circle. But there is even more. The engine probably works in combination of several simple machines and the handle that you use to push the lawnmower around the yard is a form of a lever. So even something complicated can be broken down into the simplest of machines.

Take a look around you — can you figure out what simple machines make up a can opener, the hand cranked pencil sharpener, the ice dispenser in the refrigerator or the stapler? Just be careful, though. In our modern times, many things rely on electronics and light waves to function and are not made of simple machines. But even then, you may be surprised. The turntable in your microwave oven is a wheel and axle. The lid to the laptop is connected to the pad by a hinge or lever.

Simple machines may be simple — but they are simply everywhere.

A Word or Two About Rube

Rube Goldberg Machine
Image courtesy of Jeff Kubina

Rube Goldberg was a famous cartoonist who lived between 1883 and 1970. His life was spent creating art and sculptures, but his most famous work was for his "inventions." These inventions were a series of simple machines put together in a complex fashion to accomplish something very simple, but it took many steps to get there. Contests have been run for many years since Mr. Goldberg first created his unique ideas. In the contests, people try to come up with new ways to turn on a light, or start a toaster using these combinations of the simple machines to wow judges and audiences for their unique way of doing these simple tasks.

Rube Goldberg machines are fun to watch and to build. Visit this site for some fun — see if you can identify each of the simple machines as they work together in this animation of a Rube Goldberg gadget designed to get this guy out of bed in the morning. Click here.

For more information about Rube Goldberg's life and his art, click here.

Top 10 Questions

January 2014

Thanks to Dr. Kathryn Devine, Assistant Professor of Physics, College of Idaho; and Dr. John Gardner, Director, CAES Energy Efficiency Research Institute, Boise State University for the answers.

  1. Why are they called simple machines?

    Most of the machines we work with are complicated, but they are made up of a few simple building blocks. These building blocks are the six machines. The six machines are the lever, the wedge, the pulley, the inclined plane, the screw, and the wheel and axle. Pretty much everything we have is some combination of these machines. (From Magenta at Garfield Elementary School in Boise)

  2. Who made the first simple machine?

    We do not know who made the first simple machine. Evidence of wheels and axles goes back at least 5,000 years, and wedges are known to have existed before that. Simple machines have been around for thousands of years. They originated during a time when there were no communications between the many different cultures using them. (From Veta at Basin Elementary School in Idaho City)

  3. How is work measured?

    There are different types of work, and there are different types of instruments to measure work. Physicists use a unit called joules to measure energy. You also know about calories, which are units used to measure the energy of food. Physical work, pushing a block a certain length, is a force multiplied by a distance. Work is a combination of two different physical things: force and distance. In terms of electricity, we calculate volts and amps. So, any time you are talking about work or energy, it's really two different things considered together. (From Natalee at Garfield Elementary School in Boise)

  4. What is the most useful simple machine?

    It depends on what your need is. They are all very useful and one is not anymore important than the other. The most common machine is probably the wheel. (From Drew at Riverside Elementary School in Boise)

  5. How do you make a simple machine?

    The easiest simple machine to make is the lever. You need a long, rigid bar and a fixed object to lean it against. That way the bar can pivot around the fixed object. Another easy simple machine to make is the wedge. Any small block of wood or metal that tapers to a point can be used as a wedge. Wheels are harder to make because they have to be perfectly round. (From Shelby at Kamiah Elementary School in Kamiah)

  6. How big can a machine get?

    A machine can be as big as you want it to be. The sky is the limit. The bigger the machine, the more expensive it is to make. So you would only want to make it as big as you need it to be. It's more challenging to make these machines really, really small, like the parts used in a watch. (From Audrey at Riverside Elementary School in Boise)

  7. How does a lever work?

    Energy, or work, is a force through a distance. A lever gives you a way of exerting force at another location. You push a lever at one end and it exerts force at the other end. The fulcrum is the pivot point. The amount of force exerted at the other end of the lever is dependent on the distance between the fulcrum and where the force originates. The greater the distance, the less force is exerted at the other end. The smaller the distance, the greater the force is at the other end. (From Ashton at Basin Elementary School in Idaho City)

  8. When my teacher pulls her map down, what simple machine is she using?

    She is primarily using the wheel and axle because the map wraps around a tube. The map can lock in place and spring back, so there would also be other simple machines involved also, like levers. (From Isabella at Cynthia Mann Elementary School in Boise)

  9. Who made the pulley?

    The oldest record we have of the pulley is from the third century B.C. by Archimedes. The pulley may have been around way before that, but he is the first one to have written it down in a way to survive to modern times. (From Sam at Basin Elementary School in Idaho City)

  10. Do some simple machines only come from some cultures?

    The wheel, wedge and lever were developed independently across many cultures thousands of years ago mainly because they are simple to build and invent. We're unsure of who invented the screw and pulley as they would have been trickier to build and would have required more ingenuity. (From Ben at Garfield Elementary School in Boise)