Materials Flashcards
Density Definition
Mass per unit volume
Density Equation and Measurements
Density = Mass / Volume ( Measured in kgm^-3 )
Fluid Pressure Definition
Measurement of the force per unit area that acts on an object in the fluid
Fluid Pressure Equation and Measurement
Pressure at Base = Weight of Column (Mass x Volume x GFS) / Area ( Measured in Pascals )
What is laminar flow?
When flow lines are parallel in adjacent layers of fluid and have a constant velocity so no energy dissipates.
What is turbulent flow?
When layers of fluid cross into each other and velocity is different throughout creating eddy currents and vortices which dissipate energy.
What is Archimedes Principle?
A body totally or partially immersed in fluid is subject to an upwards force in magnitude to weight of good it displaces.
Upthrust Definition and Equation
Weight of displaced fluid (Volume x Density of Fluid x GFS) measured in pascals
Weight Definition and Equation
Force on object under gravity (Volume x Density of Solid x GFS) measured in pascals.
Force ( Drag ) Definition and Equation
Force opposite to weight on object ( 6 x pi x Viscosity x Radius x Velocity )
What happens under terminal velocity?
Under terminal velocity all forces are at equilibrium this means that Weight = Upthrust + Force
Viscosity Definition and Measurements
Viscosity is the resistance between adjacent layers in laminar flow measured in Nsm^-2
Stokes Law and Equation
For a sphere moving through a fluid the viscous drag acting on it is given by the equation Force = 6 x pi x Viscosity x Radius x Velocity provided that the movement of the fluid on the sphere is laminar ( measured in pascals ).
Hardness Definition
Resistant to scratching or abrasion
Stiffness Definition
Resistant to extension
Malleable Definition
Under compression, can be beaten into a sheet but may loose strength
Ductile Definition
Under tension or extension, can be drawn into a wire but doesn’t loose strength
Strength Definition
Can withstand high stresses before failure
Brittle Definition
Fails or breaks before plastic definition
Toughness Definition
Difficult to break, absorbs energy and is resistant to dents and deformation
Elastic Deformation Definition
Returns to it’s original dimensions after the force is removed
Plastic Deformation Definition
Does not return to its original dimensions once the force is removed, the object is permanently deformed (occurs after elastic limit)
Hooked Law Definition and Equation
Force needed to extend a spring is proportional to extension of spring until it reaches the limit proportionality using equation Force = Spring Constant x Extension
What is Spring Constant measured in?
Newton metre (Nm^-1)
Elastic Potential Energy Definition
The ability of a deformed material to do work as it regains its original dimensions.
How do you calculate elastic potential energy / work done?
Using equation Elastic Potential Energy = 1/2 x Spring Constant x Extension^2
Or the area under the graph
Stress Definition and Equation
Stress is the force per unit area of a material ( Stress = Force / Area )
Strain Definition and Equation
Strain is the extension per unit length ( Strain = Extension / Original Length )
Youngs Modulus Definition
Young’s Modulus is a property of materials that undergo tensile strength or compressive stress
How do you calculate Youngs Modulus?
Youngs Modulus = Stress / Strain or the gradient of the straight section of the graph measured in Pascals.
Elastic Limit
The point beyond which an object no longer returns to its original dimensions once the force is removed.
Ultimate Tensile Strength
Maximum stress before failure
Limit of Proportionality
Max stress before Hooke’s Law stops applying.
