Workbook 2 - Materials Flashcards
What is the equation for density?
P = m/v
Density (Ro) = mass/velocity
What is the equation for the young modulus?
Young modulus = tensile stress/tensile strain =
E = FL / A delta L
If the young modulus is high, what does this mean?
That it is difficult to stretch
How can you calculate the young modulus of a graph of force against extension?
Gradient x (L / A)
Which type of objects obey Hooke’s law when a force is applied to stretch them?
Metal cables, springs etc.
What does Hooke’s Law state?
That the extension is directly proportional to the force up until the elastic limit
What can Hooke’s Law be written as?
1/2 k (delta L)^2
K = the spring constant (Nm)
Delta L = the extension (m)
What happens if you draw a graph with two variables directly proportional to each other?
A straight line through the origin
What is the gradient of a force extension graph equal to?
The spring constant k
What is the definition of work done?
The energy transferred during any physical process
How can you calculate work done?
The average force multiplied by the distance moved in the direction of the applied force
What is the work done equal to for anything being stretched?
The area under the force extension graph
What is the formula for an object that obeys Hooke’s Law?
F=k x e
What is the definition of stress?
Force per unit cross sectional area. It allows you to compare objects of different thickness
What are the units of stress?
Nm^-2 or Pa
