SIMPLE MACHINES: HISTORY, CHARACTERISTICS, TYPES, EXAMPLES - TECHNOLOGY - 2025

The simple machines are mechanical devices that change the magnitude or direction of a force. They can generally be defined as the most bare-bones apparatus that use a mechanical advantage, also called leverage, to increase a force.

Throughout history, humans have developed various devices to facilitate work. The most important are known as the six types of simple machines: the lever, the wheel and shaft, the pulley, the inclined plane, the wedge and the screw.

Source: John Mills

When you hear the word machine, you think of something like an excavator or a steam engine. However, in science a machine is anything that makes a force greater.

A machine can increase the amount of force produced, at the cost of a proportional reduction in the distance the load travels. Mechanical advantage is called the relationship between the force produced and the force applied.

A simple machine uses a single applied force that works against a single loading force. Ignoring friction losses, the work done on the load equals the work done by the applied force.

Elemental blocks

Simple machines are everywhere, being used every day to perform simple tasks. They have also been used since the earliest days of human existence.

Simple machines can be considered as the elementary blocks of which all the more complex machines are composed, called compound machines.

In the mechanism of a bicycle, for example, pulleys, levers and wheels are used. The mechanical advantage of a compound machine is nothing more than the result of the mechanical advantages of the simple machines that compose it.

However, although they continue to be considered very important in mechanics and applied science, modern mechanics has transcended that vision of simple machines as the elementary blocks of which all machines are composed.

History

Initial ideas

Around the 3rd century BC. C. originated the idea of ​​a simple machine, with the Greek philosopher Archimedes, who studied the following simple machines: lever, pulley and screw.

He discovered in the lever the principle of mechanical advantage. His famous comment regarding the lever: "Give me a place to lean and I will move the Earth" expresses his understanding that there was no limit to the amount of force increase that could be achieved with the use of mechanical advantage.

Later Greek philosophers defined five classical simple machines and were able to calculate the mechanical advantage they had.

For example, in his work Mechanics, Heron of Alexandria (10-75 AD) lists five devices that can set a load in motion: pulley, wheel and shaft, lever, screw, and wedge, detailing their manufacture and use.

However, the knowledge of the Greeks was restricted to the statics of simple machines (the balance of forces), not including dynamics, the concept of work or the trade-off between force and distance.

Renaissance period

The dynamics of mechanical forces, as simple machines were called, began to be studied during the Renaissance, from the perspective of how far a load could be lifted, in addition to the force that could be applied, which eventually led to the new concept mechanical work.

The mechanical advantage of the inclined plane was deduced by the Flemish engineer Simon Stevin in 1586. It was included alongside the other simple machines.

The Italian scientist Galileo Galilei elaborated in 1600 the complete dynamic theory of simple machines, in his work Le Meccaniche, where he revealed the underlying mathematical similarity as force amplifiers of these machines. He was the first to explain that simple machines did not create energy, they only transformed it.

Leonardo da Vinci discovered the classical rules of sliding friction in machines, but they were not published or documented in his primer. In 1699 Guillaume Amontons rediscovered these rules and in 1785 they were developed by Charles-Augustin de Coulomb.

characteristics

Simple machines are devices with no or very few moving parts, which make work easier. The main function of a simple machine is the amplification of the force or the modification of the movement.

Movement and force

Motion and force in a simple machine are inseparable. They are always in inverse relationship.

The force produced by a lever is greater than the force applied to it, but the movement produced is less than the movement applied. That is, a gain in strength is accompanied by a loss in movement.

Job

In mechanics, work is something that forces do when they move in the direction in which they are acting. That is, when a force is applied to travel a distance, work is produced. This is expressed mathematically as: Work = Force × Distance.

For example, to lift an object, work must be done that exceeds the force of gravity and thus be able to move the object up.

To lift an object twice as heavy, it takes twice as much work to lift it the same distance. It would also take twice as much work to lift the same object twice as far.

This concept of work is fundamental to define the mechanical function in simple machines in terms of force and movement, highlighting the inseparability of force and movement.

Mechanical advantage

It is the relationship between the force that performs work with respect to the applied force. Therefore, it is the force amplification effectiveness of a simple machine.

The mechanical advantage of simple machines means that less force can be used to move an object, but it has to be moved a longer distance.

Many times a task is felt to be difficult because it requires a lot of force. Using the trade-off between distance and force can make the task much easier to complete.

An example is pushing a heavy object down a ramp. It is easier to push the object down the ramp than to lift it to the correct height, but it must be carried a longer distance.

What are simple machines for?

Simple machines make work easier by performing one or more of the following functions:

- Transfer a force from one place to another.

- Change the direction of a force.

- Increase the magnitude of a force.

- Increase the distance of a force.

Although simple machines take many different forms, they come in six basic types:

- Wedge: device to separate things.

- Wheel and axle: used to reduce friction and as a force multiplier.

- Lever: moves around a fulcrum to increase or decrease mechanical advantage.

- Inclined plane: lift objects when climbing a slope.

- Screw: a device that can lift or hold items together.

- Pulley: changes the direction of a force.

Increase the applied force

Simple machines help humans increase the force applied to an object. They provide a mechanical advantage to help move objects.

As the work formula indicates, the main benefit of simple machines is allowing the same amount of work to be done by applying a lesser amount of force over a greater distance.

For example, you want to lift an object weighing 10 kilograms 2 meters off the ground. 10 kg of force can be exerted on the object in an upward direction, for a distance of 2 meters, thus doing 20 Newtons of work.

If a 3 meter lever were used, placing the object at one end and placing a 10 cm fulcrum under the bar at 1 meter distance from the object, then to lift the object you would have to push down on the other end with a force of only 5 kilograms.

However, the end of the lever would have to be pushed down 4 meters to lift the object only 2 meters.

There is a trade-off. Lowering the lever doubles the previous distance, but reduces the force required by half, doing the same amount of work.

Types

Lever

It is a kind of rigid bar that has a fixed fulcrum as a point of support. It consists of a load, which is the object to be moved or lifted, a fulcrum, which is the pivot, and an effort, which is the force required to move or lift the load.

Applying a force to one end of the lever creates a greater force at the other end. The applied force will increase or decrease depending on the distance from the fulcrum to the load and stress.

Wheel and axle

It consists of a wheel attached to a smaller axle so that these two parts rotate together, where a force is transferred from one to the other. A hinge supports the shaft, allowing rotation.

It facilitates the work of moving objects over distances. The wheel, which is the round end, rotates with the cylindrical axis, causing the movement.

It can also amplify the force. A small force applied to the circumference of a large wheel can move a larger load attached to an axle.

Pulley

It is designed to support the movement and change of direction of a taut rope. The rope wraps around a wheel. As the wheel turns, the rope moves in any direction.

If a hook is connected to the rope, the rotation of the wheel can be used to raise and lower objects, facilitating the work.

Inclined plane

It is a flat surface, with one end higher than the other, used as a support to raise or lower a load. They are widely used to move heavy loads over vertical obstacles.

Moving an object up an inclined plane requires less force than lifting it directly, at the cost of an increase in the distance traveled.

The mechanical advantage of an inclined plane is equal to the ratio of the length of the inclined surface to the height it covers.

Cradle

It is a triangular shaped tool. It can be used to separate two objects, remove pieces of an object, lift it, or hold an object in place.

It works by converting a force applied to its blunt end into forces perpendicular to its inclined surface.

The mechanical advantage is given by the relationship between the length of the slope and the width.

Screw

It is a mechanism that converts the rotational movement into linear movement and the rotational force (torque) into a linear force. A screw is really another type of inclined plane.

Its most common shape consists of a cylindrical shaft with helical grooves called threads along the outside.

The screw passes through a hole in another object or medium with internal threads that mesh with the screw threads.

Examples

Levers

Some examples of levers are door handles, claws on a nail removal hammer, iron levers, light switches, bottle openers, and hinges.

Source: pixabay.com

Wheels and axles

They are found where things go around in a circle, like an electric fan, a motor, a revolving door, a carousel, and any wheel, whether it's in the car, on a skateboard, or on a bicycle.

Source: pixabay.com

Pulleys

They are used in curtains and blinds to move them up and down, or back and forth.

They can bring something up from the ground, like a flag on a pole. The rope is pulled down, but the flag goes up.

They are also used in industry to raise and lower heavy loads, on ships to raise and lower sails, or in cranes to be used on moving construction equipment.

Elevators also use pulleys to move the car down and up from floor to floor.

Source: pixabay.com

Inclined planes

They are used in scooter parks, wheelchair ramps, and for moving heavy equipment in and out of the back of trucks.

Modified versions of a ramp are found on stairs, escalators, walking paths, and even on slides used to drop mail in the mailbox, right up to a train going up a slope.

Source: pexels.com

Cradle

Some examples of wedges used to separate can be a shovel, a knife, an ax, a pickaxe, a saw, a pair of scissors or an ice pick.

Wedges can also hold things together, as in the case of a staple, pins, tacks, nails, or doorstops.

Source: pixabay.com

Screw

Some examples are on a drill, a jar lid, a light bulb, a bolt, bottle caps, faucets, and pens.

Another use of the screw is in a device called a screw pump. It is a huge screw-shaped hydraulic machine that goes into the water. When rotating, thanks to its screw shape, the water goes up the twisted shaft, rising to where it is needed. Screw pumps are often used for irrigation and in agricultural settings such as farms.

Source: pixabay.com

References

1. Wikipedia, the free encyclopedia (2019). Simple machine. Taken from: en.wikipedia.org.
2. Idaho Public Television (2019). Simple Machines: Facts. Taken from: idahoptv.org.
3. Jim Lucas (2018). 6 Simple Machines: Making Work Easier. Live Science. Taken from: livescience.com.
4. Teach Engineering (2019). Engineering: Simple Machines. Taken from: teachengineering.org.
5. For Teachers for Students (2019). What are simple machines? Taken from: forteachersforstudents.com.au.
6. Victoria State Government (2019). Simple machines. Taken from: education.vic.gov.au.
7. Vex IQ (2019). The Six Types of Simple Machines. Taken from: vexrobotics.com.