Materials Flashcards
(20 cards)
Archimedes’ Principle
When a body is submerged in water it experiences an upthrust equal to its fluid displaced
Breaking stress
The maximus stress a material can withstand without fracturing
Brittle
A material that fractures without plastic deformation first
Density
Mass divide by volume in kgm^3
Ductile
A material that can withstand large plastic deformation allowing it to be stretched into long wires.
Elastic deformation
When a material can return to its original shape after an applied stress, without permanent change to its shape. Work done elastically deforming an object is stored as elastic strain energy
Elastic limit
The maximum stress that can be applied to an object without plastic deformation
Hooke’s Law
The extension of an object is directly proportional to the force applied
Laminar flow
A state of flow where layers of fluid move together in parallel with little to no mixing of layers
Limit of proportionality
The point at which the stress on an object is so high Hooke’s Law no longer applies
Plastic deformation
When a material is permanently deformed after an applied stress
Stoke’s Law
The magnitude of the force of viscosity acting on a spherical body as it moves
through a fluid is proportional to its radius, its velocity and the fluid’s viscosity. This only
applies to spherical bodies travelling in laminar, non-turbulent, flow.
Tensile strain
The extension of an object divided by its original length
Tensile stress
The internal resistance of an object against a force that acts to deform it. It is
the force applied per unit cross-sectional area
Turbulent flow
A state of flow where layers of fluid mix together unpredictably causing a
chaotic state.
Viscosity
A quantity measuring the internal friction of a fluid, it acts to reduce the flow of a
fluid. It is temperature dependent
Upthrust
The force felt against the weight of an object when fully or partially submerged in a
fluid. It is equal to the weight of the fluid displaced by the object.
Yield point
The point on a force-extension graph at which a material begins to rapidly
extend without any additional stress.
Young’s modulus
The ratio of stress to strain of an object. It is a measure of how stiff a material is.
