6.1 Deformation of Solids Flashcards
Stress and Strain
6.1.1 What causes deformation?
Deformation is called by tensile or compressive forces.
What is a tensile force?
When two forces stretch a body.
What is a compressive force?
When two forces compress a body.
6.1.2 What is a load attached to the end of a spring?
A load applies a force to the spring.
6.1.2 What is the extension?
When an object’s length increases from what it was originally. Extension is measured by subtracting the original length from the final.
6.1.2 What is compression?
When an object’s length decreases from what it originally. compression measured by subtracting the final length from the original.
6.1.2 What is the difference between the limit of proportionality and the elastic limit?
The limit of proportionality is the point at which the force-extension graph changes from the linear to the non-linear region. Whereas the elastic limit is the maximum stress or force per unit area that a solid material can withstand before permanent deformation.
6.1.3 State Hooke’s law:
Hooke’s Law is the extension of an elastic object is directly proportional to the force applied, up to the limit of proportionality
6.1.4 What is the relationship between spring constant, force, and extension?
k = F/x
k = Spring constant in Nm^-1
F = Force in N
x = Extension in m
6.1.5 What is stress?
Tensile stress is the applied force per unit cross sectional area of a material.
or
σ = T/A where
σ is tensile stress in Pa
F is applied force in N
A is area in m^2
6.1.5 What is strain?
Strain is the extension per unit length and is a ratio.
or
ε = x/L
where ε = strain
x = extension in m
L = length in m
6.1.5 What is Young’s Modulus, and what units are used?
The Young Modulus is defined as the ratio of stress and strain.
Young modulus is a measure of how stiff or elastic a material is.
6.1.5 What is the equation for Young’s Modulus, and add units:
E = σ/ε
E = Young’s Modulus in Pa
σ = Strain in Pa
ε = Stress that is a ratio
