Choosing suitable materials
Transcript
Imagine you have arrived on Earth from another galaxy.
You need to pick materials that will help you survive in your new environment.
You could do this by testing the properties of different materials.
These are the qualities that affect how they are used.
To stay dry, it would be pointless making a shelter out of sponge.
The water would pass through the sponge because it is permeable.
permeable
A better choice would be a waterproof sheet of plastic tarpaulin.
waterproof
Plastic is also flexible, so you can shape it easily into a shelter, and it is durable, so it will last a long time.
flexible
durable
What material would you choose to sleep on?
Not metal – it's hard and it's a thermal conductor.
hard
thermal conductor
It wouldn't be comfortable and would carry heat away from your body, so you would become cold.
A soft foam mattress that is a thermal insulator would be much more comfortable, and would keep you warm.
soft
thermal insulator
You will also need to find food.
If you made a raft you could go fishing.
What material would be best for this job?
It needs to be readily available, strong enough to bear your weight, and, of course, it needs to float.
strong
A wooden boat would be perfect.
float
Now all you need is to find a material that will burn so you can cook your dinner. Any thoughts?
The properties of a material will affect how it is used.
Imagine you are from another galaxy. You have just arrived on Earth.
You need materials that will help you survive here.
To choose the right materials, you need to test their properties.
Properties are features that affect how a material is used.
What will you use to build a shelter?
A shelter made of sponge would not keep you very dry.
Water would pass through, because sponge is permeable.
permeable
Plastic would be better, because it is waterproof
waterproof
Plastic is also flexible, so it can be shaped into a shelter. And it is durable, so it will last a long time.
flexible
durable
What material would you choose to sleep on?
Metal would be uncomfortable, because it is hard. It is also a thermal conductor.
hard
thermal conductor
This means it would carry heat away from your body, making you feel cold.
A foam mattress is soft, and it is a thermal insulator. So, this material would be comfortable and warm.
soft
thermal insulator
You will also need to find food.
If you made a boat, you could go fishing.
What material would you use to make a boat?
It needs to be easy to find. It needs to be strong enough to carry you. And it needs to float.
strong
Wood is a good choice of material for a boat.
float
Now you need a material that burns, so you can make a fire to cook your dinner. Do you have any ideas?
The properties of a material will affect how it is used.
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