Materials Flashcards
(16 cards)
What is density?
Mass per unit volume
Formula: ρ = m/V, where ρ = density, m = mass, V = volume.
What does Archimedes’ principle state?
The buoyant force experienced by an object is equal to the weight of the fluid it displaces
If an object’s density is lower than water, it will float.
What is Hooke’s law?
The amount of extension experienced by a material is directly proportional to the force applied to it, up to the limit of proportionality
Formula: F = k * ΔL, where F = force, k = spring constant, ΔL = extension.
What is elastic deformation?
Elastic deformation occurs when a material returns to its original shape after the force is removed
It obeys Hooke’s law up to the limit of proportionality.
What happens past the limit of proportionality?
Materials may undergo a bit more elastic deformation before plastic deformation starts, but this will no longer be directly proportional.
What is plastic deformation?
Plastic deformation occurs when individual atoms within a material begin to slide over one another, causing permanent deformation.
Gradient of a force-extension graph?
Spring constant
Area underneath a force-extension graph?
Work done/energy stored by the material
What is elastic hysteresis?
When a material has different loading and unloading curves on a force/extension graph, due to internal friction
What is stress?
Stress is given by the force acting on a material divided by the cross-sectional area perpendicular to the direction of the force
Formula: σ = F/A, where σ = stress, F = force, A = area.
What is strain?
Strain is the ratio between the original length of a material and the extension it experiences under load
Formula: ε = Δl/l, where ε = strain, Δl = extension, l = original length.
What is Young’s modulus?
Young’s modulus is an intrinsic property of a material that describes how much it will extend under tension
Measured in Pascals.
What does a stress-strain graph represent?
Stress-strain graphs show the relationship between stress and strain, with the area under the graph representing work done per unit volume.
Gradient of a stress-strain graph?
Young’s modulus
Area underneath a stress-strain graph?
Work done per unit volume
What is a brittle material?
A brittle material deforms very little before breaking and does not undergo plastic deformation.
