What is Hooke’s Law
Extension of a stretched object is proportional to the load
What is the limit of proportionality?
When metals stop obeying Hooke’s Law
What happens when load is increased past the elastic limit?
The material will be permanently stretched and can’t return to original length
What is elastic deformation?
When the material returns to its original shape and size once forces have been removed
What is plastic deformation?
When a material is permanently stretched
What is ultimate tensile stress?
The maximum stress a material can withstand
What is work done in stretching a string stored as?
Elastic strain energy
What is Young modulus a measure of?
Stiffness
Units of Young modulus
Nm^-2 or pascals
Formula for Young modulus
(Force x initial length)/(extension x cross-sectional area)
What is the area under an Stress-Strain graph?
Energy stored per metre cubed of of wire
What is the yield point?
Where material starts to stretch without extra load. It’s the stress at which large amount of plastic deformation takes place
2 main differences of a graph for a brittle material
Straight line
Suddenly fractures instead of deforming
What do force-extension graphs contain that stress-strain graphs dont
Unloading
