What are the properties of solids?
- They keep their own shape unless pulled twisted or bent.
- the particles are very close together.
- the particles cannot be compressed
- they have a fixed volume
What states do most materials exist in?
Solids, liquids and gases.
What are the properties of liquids?
- they do not keep their shape.They take the shape of the container they’re in.
- they flow.
- they are compressed with great difficulty.
- gravitypulls a liquid to the bottom of a container.
What are the properties of gases?
- they do not keep their shape. They fill the container completely.
- they flow
- they can be compressed
- they have mass because they are affected by gravity.
What are gases also known as?
Vapours
How can the shape of an object be changed?
By using force.
What are the basic forces?
Pushing and pulling
When you push an object what are you doing?
Compressing it.
When you pull an object what are you doing to it?
Stretching it.
How can you change the direction of these pushing and pulling forces?
By twisting,bending or shearing.
How do engineers use forces when they design buildings?
They use materials that can resist different forces so that the buildings do not collapse. Different materials have different properties and have different strengths . And they respond differently to the forces exerted on them.
What properties do all materials have?
Hardness, toughness, stiffness,flexibility and strength under tension.
What is hardness?
The property of a material to resist being scratched, cut or dented.
What is toughness?
The measure of the strength of a material before it will break.
What is stiffness?
It is a measure of how much a material will resist being bent.
What is flexibility ?
How much a material can bend without breaking.
What is strength under tension?
When a rope is stretched and pulled tight it is under tension.
