materials - physics

Define tensile forces

Equal and opposite forces acting on a material to stretch it

Define compressive forces

Two or more forces together that reduce the length or volume of an object

Tensile deformation

A permanent change in the shape of an object due to opposite forces stretching the material

Compressive deformation

A change in the shape of an object due to opposite forces pushing against the material

Extension

The increase in the length of an object when tensile forces are exerted on it

What is Hooke’s law?

The force applied to an elastic object is directly proportional to its extension

What does the gradient of a force extension graph represent

The force constant

How do you find work done from a force extension graph

The area under the graph

What happens when the spring is stretched beyond the elastic limit, and then unstretched?

The spring doesn't return to it's original shape. Permanent deformation has occured

Derive elastic potential energy equation

Force x extension = work done = EPE

Describe the spring and force constant when they are added in parallel

The extension decreases and the spring gets more stiff

The force constant increases

Describe the spring and force constant the they are added in series

Extension increases, spring gets less stiff

The force constant decreases

Define tensile stress

Force per unit area

Define tensile strain

Extension per unit length

What is the equation for Young's modulus

Stress/strain

Limit of proportionality

point up to which stress is proportional to strain, or force is proportional to extension

Yield point

point at which the material begins to stretch without an increase in force

Elastic limit

point at which elastic deformation becomes plastic deformation, and the material will no longer return to its original shape and size when unstretched

Ultimate tensile stress

maximum stress that a material can withstand before it breaks

Breaking point

point at which the material breaks/fractures

Elastic region

region in which a material returns to its original length when unstretched

Strain-hardening region

region in which a material becomes stronger through permanent plastic deformation

Plastic region

region in which a material does not return to its original length when unstretched

Necking region

region in which the tensile force in a material begins to localise in a smaller cross-sectional area, resulting in a decreased stress as strain increases and ending in fracture