Materials Flashcards
Define pressure, density and volume
Pressure: force per unit area
Density: mass per unit volume
Volume: quantity of three-dimensional space enclosed by a closed surface
Rule of upthrust
Force of upthrust = weight of fluid displaced
State stokes’s law
F = 6πηrv
Difference between laminar and turbulent flow
Laminar flow is when the layers flow parallel to each other and don’t interact. It is a smooth flow and there is a constant speed.
Turbulent flow is when the layers can cross over each other and turn at angles. No constant speed.
Why does Stoke’s law only apply for small objects and laminar flow?
If the object is not small, there may be friction with the sides of the tube it is going down, causing turbulent flow. When there is turbulent flow, he characteristics of the object’s movement are unpredictable, therefore the velocity is not terminal/constant
What is Hooke’d Law
F=kx
Equations for stress, strain and young modulus and the definition
Stress = force / cross-sectional area
Strain = change in length / original length
Young’s Modulus = stress / strain
Young’s Modulus: measure of elasticity (how stiff an object is)
Explain:
Limit of proportionality
Elastic limit
Yield point
Elastic deformation
Plastic deformation
Limit of Proportionality: the point beyond which Hooke’s law is no longer true when stretching a material.
Elastic Limit: the point beyond which the material you are stretching becomes permanently
stretched so that the material does not return to its original length when the force is removed.
Yield Point: the stress at which a material begins to deform plastically.
Elastic Deformation: The object will return to its original shape after the force is removed. Plastic Deformation: The object will permanently deform.
Equation to calculate the elastic strain energy
1/2 kx^2
Define:
Hard
Brittle
Ductile
Malleable
Strong
Tough
Stiff
● Hard - Can scratch or indent, and withstands being scratched.
● Brittle - Breaks without plastic deformation.
● Ductile - Can be drawn into a wire.
● Malleable - Can be reshaped.
● Strong - Withstands large static loads without breaking.
● Tough - Withstands large dynamic loads without breaking.
● Stiff - Resists deformation by tension or compression.
Stiffness equation if springs are in series or parallel
Series: k = 1 / ((1/k1)+(1/k2))
Parallel: k = k1 + k2
What is the ultimate tensile strength
The maximum stress that the material can withstand. At this point, breaking stress occurs and the atoms of the material separate completely, causing it to break.
