https://padlet.com/zameer_ahmed/materialsphy025 People have been using, and altering, the properties of materials since the Stone Age. Flint tools, samurai swords and glass beakers all made use of the strength, flexibility or optical properties of the materials they were created from. Today, engineering materials researchers use their knowledge of the properties of materials to develop novel materials, and find new uses for old ones. en-us 2021-02-16 03:24:45 UTC 2025-04-24 05:12:32 UTC hello@padlet.com zameer_ahmed https://padlet.com/zameer_ahmed/materialsphy025/wish/2551304867 The density of a material is a measure of the mass per unit volume. It is given the symbol, ρ. Density is a useful quantity because it allows us to compare different materials ]]> 2023-04-12 07:49:42 UTC https://padlet.com/zameer_ahmed/materialsphy025/wish/2551304867 zameer_ahmed https://padlet.com/zameer_ahmed/materialsphy025/wish/2551314822 the extension was proportional to the force applied.
extension ∝ force
Δl ∝ F

We can therefore write Hooke’s law as:
F = kΔl
where
F is the applied force in N
k is the spring constant in N m−1
Δl is extension in m]]> 2023-04-12 08:01:04 UTC https://padlet.com/zameer_ahmed/materialsphy025/wish/2551314822 zameer_ahmed https://padlet.com/zameer_ahmed/materialsphy025/wish/2551315797 2023-04-12 08:02:05 UTC https://padlet.com/zameer_ahmed/materialsphy025/wish/2551315797 zameer_ahmed https://padlet.com/zameer_ahmed/materialsphy025/wish/2551317016 2023-04-12 08:03:42 UTC https://padlet.com/zameer_ahmed/materialsphy025/wish/2551317016 zameer_ahmed https://padlet.com/zameer_ahmed/materialsphy025/wish/2551318778 2023-04-12 08:06:09 UTC https://padlet.com/zameer_ahmed/materialsphy025/wish/2551318778 zameer_ahmed https://padlet.com/zameer_ahmed/materialsphy025/wish/2551319314 2023-04-12 08:06:45 UTC https://padlet.com/zameer_ahmed/materialsphy025/wish/2551319314 zameer_ahmed https://padlet.com/zameer_ahmed/materialsphy025/wish/2551319796 Ductile materials can be formed into wires
by stretching them. They show ductility.

Wires obey Hooke’s law because the bonds between the metal atoms act like springs. When the wire is stretched the bonds lengthen slightly. When the force is removed, the bonds return to their original length.

However, if the force applied is too great, and the elastic limit exceeded, then the metal atoms will be able to move past one another and the wire lengthens. This is known as ductility, and is a very useful property as it allows metals to be formed into thin wires.]]> 2023-04-12 08:07:20 UTC https://padlet.com/zameer_ahmed/materialsphy025/wish/2551319796 zameer_ahmed https://padlet.com/zameer_ahmed/materialsphy025/wish/2551320384 A brittle material is one that shows little, or
no, plastic deformation before breaking.

Some materials do not show plastic behaviour but are brittle and break when the elastic limit is exceeded. Cast iron and glass are two examples of brittle materials. Figure 12.13 shows a typical force–extension graph for high-carbon steel, which is also a brittle material. The material fractures and breaks. It does not show plastic behaviour.]]> 2023-04-12 08:07:56 UTC https://padlet.com/zameer_ahmed/materialsphy025/wish/2551320384 zameer_ahmed https://padlet.com/zameer_ahmed/materialsphy025/wish/2551323456 The way in which ductile and brittle materials fracture is also different. Ina ductile material, the sample of material will elongate and ‘neck’ before itbreaks. On a force–extension graph, necking occurs in the plastic regionof the graph. In a brittle material there is no change in the shape of thematerial because it does not undergo plastic behaviour. A straight breakin the material is seen.]]> 2023-04-12 08:11:24 UTC https://padlet.com/zameer_ahmed/materialsphy025/wish/2551323456 zameer_ahmed https://padlet.com/zameer_ahmed/materialsphy025/wish/2551324560 elastic strain energy = 1/2 × F × Δl]]> 2023-04-12 08:12:53 UTC https://padlet.com/zameer_ahmed/materialsphy025/wish/2551324560