A-level Physics/Forces and Motion/Deformation of solids

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Hooke's law[edit | edit source]

This applies to an object's deformation only before the elastic limit; from then on it deforms plastically and no longer follows this law. it states that, extension is directly proportional to the applied force.

Spring Constant[edit | edit source]

The gradient refers to the gradient of a Tension-Extension graph.
The standard units of k are N m−1

Strain[edit | edit source]

Because this is a division of two measurements of length, Strain has no units and remains a ratio.

It can also be represented as

Stress[edit | edit source]

The units for Stress are N m−2, otherwise known as Pascals (Pa)

The Young's modulus[edit | edit source]

Strain energy[edit | edit source]

However, due to Hooke's Law, it can be calculated in another form, y=mx+c;

Elastic limit[edit | edit source]

the maximum extent to which a solid may be stretched without permanent alteration of size or shape.

Plastic limit[edit | edit source]

When the stress is sufficient to permanently deform the metal, it is called plastic deformation.