Simple Machines: Facts

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; thelever, 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 Newtons. 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 higher 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.

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.

The Inclined Plane

The inclined plane is simply a ramp. One end is higher than the opposite end. This allows things to go from a low place to a higher place. Or vice versa. It takes less work to move an object up a ramp then it does to lift that object up the verticaldistance. 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 WedgeSome 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 PulleyThe 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, inindustry 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 ScrewThe 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

Work is the amount of energy necessary to move an object. 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. It is abbreviated with a capital N. The term joule is often used to measure work as Newtons per meter. If it takes 1 Newton to move any object 1 meter, then that is equivalent to a joule.

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. Really very 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.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 RubeRube 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.

A machine is something that makes it easier for us to do work, such as moving

objects. Simple machines are ones which have only one part to do the work. One

example of a simple machine is a lever (see Diagram 1).

More complicated machines (sometimes called Compound Machines) are made up of a

number of simple machines that work together to help do the work. A wheelbarrow is one

example of a compound machine because it has levers (handles) and a wheel (see Diagram

2).

Load, effort and mechanical advantageThe load is the object that is moved. In Diagram 1, the load is the weight of the rock.

The effort is the force that is used to do the work. In Diagram 1, the effort is the force that

the person applies to the crowbar to move the rock.

You can use a simple machine to move a large load with a smaller effort than you would

need if you did not have a machine to help you. This is called gaining a mechanical

advantage.

Types of simple machinesThere are a number of different types of simple machines. These include:

Inclined planes

Levers

Pulleys

Wheels and axles

Wedges

Screws

Gears

Compound machines are made up of a combination of these simple machines. Can you

identify all the simple machines in the Simple Machines Animation?

Inclined planesAn inclined plane is a flat surface that is at an angle to the load. This type of 'machine' has

no parts that move.

An example of an inclined plane is a ramp for wheelchairs (see Diagram 3). The inclined

plane of the ramp makes it easier for the person in the wheelchair to move up into a

building.

The steeper the slope of the inclined plane, the more effort it takes to move the person in

the wheelchair up the slope.

Some other examples of inclined planes include:

roads leading up slopes

car ramps in parking stations

staircases for people to walk up and down.

You will agree that it is easier to walk up a ramp or a staircase than to climb to the same

height up a ladder.

How many examples of inclined planes did you find in the Simple Machines Animation?

LeversA lever is a rigid bar that rotates around a fixed point. This balancing point is called

the fulcrum. A lever uses a force (or effort) to make the load move.

There are different types of levers, depending on where the load, the effort, and the

fulcrum (balancing point) are positioned. For this reason, levers are classified into 3

separate groups: Class 1, Class 2, and Class 3.

Class 1 lever: This is where the fulcrum is between the load and the effort.

One example would be using a screwdriver to open a can of paint (see Diagram 4). In

this case, the screwdriver is the lever.

Imagine how much harder it would be if you had to lift the lid off a paint can with

your fingers, without the help of a lever!

Pushing down on the lever (the screwdriver) raises the load (the paint can lid).

Other examples of Class 1 levers include:

o using a bottle opener to open a bottle of drink

o using a claw hammer to pull out a nail

o playing on a see-saw.

Class 2 lever: This is where the fulcrum is at one end of the lever, the effort is at

the other end, and the load is in between.

One example would be a person lifting a load in a wheelbarrow (see Diagram 5). In

this case, the wheelbarrow and its handles are the lever, the load is the weight in the

wheelbarrow, and the force applied by the person lifting the handles is the effort.

The fulcrum (the balance point of the lever) is the axle of the wheelbarrow.

Other examples of Class 2 levers include:

o staplers that staple sheets of paper together

o nutcrackers that have the hinge at the end of the machine.

Class 3 lever: This is where the fulcrum is at one end of the lever, the load is at the

other end, and the effort is in between. These levers involve using a large effort to

move a small load a long distance.

An example is a person playing golf (see Diagram 6). In this case the golf club plus

the person's arms is the lever, the golfer's shoulder is the fulcrum, the force being

applied to the golf club by the golfer's hands is the effort, and the load is the weight

of the golf ball.

Other examples of Class 3 levers include:

o using a cricket bat, a tennis racquet or a hockey stick to hit a ball

o using a fishing rod to cast a fishing line.

There are many levers in the Simple Machines Animation. How many can you spot?

Levers in balanceA see-saw is actually a lever with a fulcrum (balancing point) in the middle (see Diagram 7).

Think about a see-saw with two people sitting at different distances from the fulcrum. If one

person is twice as heavy as the other, the lighter person must sit further away from the

fulcrum than the heavier person for the see-saw to be balanced.

Once balanced, it requires very little force for each person to push the see-saw up and

down with their legs.

Wheels and axlesA wheel and axle is a simple machine that is made up of a smaller cylinder (the axle) joined

to a larger cylinder (the wheel).

Often a wheel and axle is used to make it much easier to move a load. An example of this

is a trolley, or any other wheeled vehicle (see Diagram 8). You will agree that it would be

much easier to move a heavy load across the ground with a trolley that does have wheels

rather than with a trolley that does not have wheels.

There are two examples of wheels and axles in the Simple Machines Animation. See if you

can find them.

PulleysA pulley consists of a rope (or a belt or chain) that passes around a wheel.

Fixed pulleysAn example of a fixed pulley would be a pulley at the top of a flagpole (see Diagram 9).

Because of the pulley at the top, the person raising the flag can stand on the ground and

hoist the flag by pulling down on the rope. Imagine how much harder it would be without a

pulley - the person would need to climb up the flagpole with the flag!

Other examples of fixed pulleys include:

the pulley at the top of a yacht mast. The deckhand can raise the sail up the mast by

pulling down on the rope.

the pulley at the end of the boom of a crane. The crane works by pulling upwards to

lift the load.

Did you spot the two examples of pulleys in the Simple Machines Animation?

Moving pulleysDiagram 10 shows one moving pulley attached to the engine (the load), and one fixed

pulley attached to the support above. This type of pulley system is called a 'block and

tackle', where 'block' refers to the pulleys and 'tackle' is the chain that the person is pulling

to lift the engine.

WedgesA good example of a wedge is an axe, where the head of the axe is made up of two inclined

planes which do the work.

Think about an axe being used to chop and split a piece of firewood (see Diagram 11). The

axe is actually being used to change the direction of the force. Theforce of the axe blow is

downwards, but the wedge changes this downward force into two sideways forces, causing

the wood to split apart.

Other examples of wedges include:

a knife blade

a chisel used in woodworking

the point at the end of a nail

a doorstop that is wedged under a door to prevent it from moving.

Did you spot the wedge used in the Simple Machines Animation?

ScrewsA screw is really an inclined plane that is coiled around a shaft (see Diagram 12).

Some examples of screws include:

wood screws

the screw in a car jack

the screw on the lid of a jar

the blades of a fan

the blades of an aeroplane propeller.

Did you notice the screw in the Simple Machines Animation?

GearsGears are toothed wheels that fit together so that when one gear turns it also turns the

other gear. Sometimes the gears fit directly together, and sometimes they work together

through a chain or a belt (see Diagram 13).

Look at the animated gears. The big one has 40 teeth, and the small one has 20 teeth.

Suppose that the big gear is being used to drive the small gear. Each time the big gear

rotates once, it uses all its 40 teeth. The small gear has only 20 teeth, so it is rotated twice.

This is producing a gain in distance.

On the other hand, suppose that the small gear is being used to drive the big gear. In this

case, the small gear will need to rotate twice in order to turn the big gear around once. This

is producing a gain in force.

Click on the gears to see them work.

Some examples of the use of gears include:

mechanical clocks

car gearbox and drive systems

electric drills

VCR, CD and DVD players.

Did you notice how gears were used in the Simple Machines Animation? How many

examples could you find?