Simple machines (p3)

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Jesús Manzaneque & María Montes

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MACHINES HELP US

What is a machine?

A machine is an object made up of one or more parts. It helps us to do a task, saving time and effort.

For example, it is much easier to cut a piece of paper with scissors than it is by using our fingers. It is also quicker to make pureed food with a mixer than by hand.

 

Why do we use machines?

We use machines to do diverse tasks, for example:

● To move heavy objects, we can use a construction crane or a ramp.

● To go from one place to another, we can travel by trains, planes and cars.

● To cut wood or other materials, we can use saws.

● To have a good time, we can watch videos.

● To help us with household tasks, we can use a washing machine or a dishwasher.


 

Types of machines

There are two types of machines:

● Simple machines. These are made of very few parts. A pulley, a lever and a ramp are simple machines.

● Compound machines. These are made of various simple machines joined together. A bicycle, a watch and a mixer are compound machines. 2

 

How do machines work?

Some machines work because they are moved by people or animals. For example, a bicycle moves because a person moves the pedals. When the person stops pedalling, the bicycle eventually stops.

In the same way, a cart moves because an animal pulls it.

Other examples of machines moved by people include a hammer, pliers, a broom and a wheelchair.

On the other hand, some machines need electricity or fuel to work, even though there may also be a person controlling them. For example,

buses and cars need fuel. This fuel can be either petrol or diesel. A computer and a mixer also need electricity to work.

Many machines have an engine or motor to make them move.

For example, a fan or a lorry.

 

EXAMPLES OF MACHINES (glossary)

Simple Machine:


A machine with few or no moving parts. Simple machines make work easier.


Examples: Screw, Wheel and Axle, Wedge, Pulley, Inclined Plane, Lever

Compound Machine:


Two or more simple machines working together to make work easier.


Examples: Wheelbarrow, Can Opener, Bicycle





Pulley:

A wheel that usually has a groove around the outside edge. This groove is for a rope or belt to move around the pulley. Pulling down on the rope can lift an object attached to the rope. Work is made easier because pulling down on the rope is made easier due to gravity.


Examples: Flag Pole, Crane, Mini-Blinds





Lever:

A straight rod or board that pivots on a point known as a fulcrum. The fulcrum can be moved depending on the weight of the object to be lifted or the force you wish to exert. Pushing down on one end of a lever results in the upward motion of the opposite end of the fulcrum.


Examples: Door on Hinges, Seesaw, Hammer, Bottle Opener



Wedge:

Two inclined planes joined back to back. Wedges are used to split things.


Examples: Axe, Zipper, Knife

Gears:

Two toothed wheels fit together either directly or through a chain or belt so one wheel will turn the other. Some gears may have a screw or a toothed shaft in place of one of the wheels. A gear may also be a combination of toothed wheels that produces a certain speed (such as a bicycle's top gear which makes the bike go fast, and the low gear for slow speed.)


Examples: Clock, Automobile, Drill




Inclined plane:

A sloping surface, such as a ramp. An inclined plane can be used to alter the effort and distance involved in doing work, such as lifting loads. The trade-off is that an object must be moved a longer distance than if it was lifted straight up, but less force is needed.


Examples: Staircase, Ramp, Bottom of a Bath Tub




Wheel and Axle:

A wheel and axle has a larger wheel (or wheels) connected by a smaller cylinder (axle) and is fastened to the wheel so that they turn together. When the axle is turned, the wheel moves a greater distance than the axle, but less force is needed to move it. The axle moves a shorter distance, but it takes greater force to move it.


Examples: Door Knob, Wagon, Toy Car



Screw:

An inclined plane wrapped around a shaft or cylinder. This inclined plane allows the screw to move itself or to move an object or material surrounding it when rotated.


Examples: Bolt, Spiral Staircase





Leonardo da Vinci's inventions.