Physics - Recall for Chapter 6; Materials
Recall Questions
Define Hooke’s law?
The extension of a spring is directly proportional to the force applied, provided the elastic limit of the spring is not exceeded.
Define extension?
The difference between the final and initial length of an object.
Define elastic deformation?
The material returns to its original shape and size after any applied forces are removed.
Define plastic deformation?
The material will not return to its original shape and size after any applied forces are removed. It has been permanently deformed.
Define the elastic limit of a material?
The point beyond which a material becomes permanently deformed and does not return to its original shape and size after any applied forces are removed.
What is the area under a force-extension graph equal to?
The work done by the force.
Define tensile stress?
The force per unit cross-sectional area.
Define tensile strain?
The extension (or compression) of an object divided by its original length.
Define the Young modulus of a material?
The Young modulus is the tensile stress divided by the tensile strain.
Define the limit of proportionality of an object?
The point up to which an object’s stress and strain are proprtional to each other.
How can the Young modulus of a material be found?
From the gradient of the initial straight-line section of the object’s stress-strain graph.
What does the area under the straight-line section of a material’s stress-strain graph represent?
The energy stored in the material per unit volume.
Define the breaking stress of a material?
The value of the stress at which the material snaps or breaks.
Define the ultimate tensile stress (UTS) of a material?
The maximum stress thye material experiences.
What type of materials have a high Young modulus?
Stiff materials.
What type of materials have a high ultimate tensile stress and breaking point?
Strong materials.
What is meant by a ductile material?
A material that undergoes significant plastic deformation after deforming elastically.
What is meant by a brittle material?
A material that snaps after deforming elastically and does not deform plastically.
What is meant by a polymeric material?
A material of long-chain moleculues that will deform elastically.
What is an example of a ductile material?
Metal used for making wires.
What is an example of a brittle material?
Glass or cast iron.
What is an example of a polymeric material?
Rubber.