How do you define brittle materials?
If you apply a force to a brittle material it will suddenly snap when the force exceeds a certain point. Brittle materials can also be quite weak if they hav cracks in them.
Give an example of a brittle material?
- A chocolate bar
- Ceramics (E.g. glass and pottery)
How do you define ductile materials?
You can change the shape of ductile materials by drawing them into wires or other shapes. They keep their strength when they're deformed.
Give an example of a ductile material.
- Copper (With its high electrical conductivity this means its ideal for electric wires).
What are the properties of malleable materials?
They change shape but may lose their strength. Their shape can be changed fairly easily (e.g. by hammering or rolling).
What is the difference between ductile and malleable materials?
Malleable materials won't necessarily kepp their strength.
Give some examples of malleable materials.
Define hard materials.
They are very resistant to cutting, indentation and abrasion.
Give some examples of hard materials.
- Cutting tools (e.g. chisels)
- Diamond (the hardest material known to man.)
Define stiff materials.
They have a high resistance to bending and stretching.
Give some examples of stiff materials.
- Safety helmets
- Safety boots (need to be very stiff so that they don't crush your body when they expierience impact, yet still keep their shape.)
What are stiff materials measured in?
The stiffness is measured by the Young Modulus (the higher the value, the stiffer the material).
What are the properties of tough materials?
Touhghness is a measure of the energy a material can absorb before it breaks. They are really difficult to break, as they can absorb a lot of energy.
What are some examples of tough materials?
- Some polymers-
- Some types of polythene
- The hullm of a kayak (so as it wont break on rocks).
What is Hookes Law?
Force (F) (N)=Constant (K) X Extention (x) (m)
What is Hookes?
Force is directly proportional to extention.
What does Youngs Modulus mesasure?
The stiffness of a substance.
What is Youngs Modulus measured in?
Pascals (Pa) or Nm-2
What is the equation of Youngs Modulus?
Stress (Pa) / Strain (No unit)
What is an alternative way of working out Youngs Modulus?
E (Pa) = Force (F) (N) X Length (L) (m)
Extention (x) (m) X Area (A) (m2)
What is the equation for Stress?
Stress (Pa) = Force (F) (N)
Area (A) (m2)
What is the equation for Strain?
Strain (No unit) = Extention (x) (m)
Length (L) (m)