6.1-6.4 Materials Quizlet Cards Flashcards
What is a tensile force?
A force produces an extension of the object.
What is a compressive force?
A force that reduces the length of an object.
What is Hooke’s Law?
Force is proportional to extension so long as the elastic limit is not exceeded.
What is elastic deformation?
When an object will return to its original shape when the load is removed.
What is plastic deformation?
A permanent change in shape that remains once the load is removed.
What is k in F = kx
The force constant.
What are the units of force constant (k)
Nm⁻¹
What is represented by the area under a force-extension graph?
The work done stretching the object.
What is meant by an elastic material?
A material which can be significantly deformed and will return to it’s original shape.
What is tensile stress?
The force applied per unit cross sectional area.
What is tensile strain?
The fractional change in length of an object.
What is a ductile material?
A material which can be drawn into a wire of hammered into thin sheets.
What is the limit of proportionality of a material?
The point at which a material stops obeying Hooke’s Law
What is the elastic limit of a material?
The point at which a material starts to plastically deform.
What is the yield point of a material?
The point at which the material starts to extend rapidly as stress increases.
What is the ultimate tensile strength of a material?
The maximum stress a material can withstand before breaking.
What is the breaking strength of a material?
The stress at the point of fracture.
What is a strong material?
One with a high ultimate tensile strength.
What are the units of Young Modulus?
Pa OR Nm⁻²
When does the Young Modulus apply to a material?
When stress is proportional to strain OR when it is obeying Hooke’s law
How do you find the Young Modulus from a stress-strain graph?
The gradient of the initial straight line region.
What material property does Young Modulus measure?
The stiffness.
What is a brittle material?
A material the show only elastic behaviour up to its breaking point, without plastically deforming.
What is a polymeric material?
A material made from long chain molecules.
