Materials Flashcards
What type of energy is stored in an object that has been stretched?
Elastic potential energy
What is the yield point?
The point at which the object will experience a large extension without an increase in stress
What does the area underneath a force-extension graph represent?
The area us equal to the elastic potential energy stored in the spring
What unit is the Young’s Modulus measured in?
Nm⁻² or Pa
State the equation for Young’s Modulus.
Stress / Strain
What is the unit of strain?
There is no unit, it is a ratio of the extension and original length
State the equation of strain?
Extension / Original length
What is elastic deformation?
Deformation where a material can return to its original shape and size, after an applied stress is released. Any work done is stored as elastic potential energy
Why will a uniform object with a density greater than that of the fluid it is submerged in, always sink?
- Upthrust = weight of displaced fluid
So therefore maximum upthrust is ρ(f)Vg - Weight = ρ(o)Vg
Therfore if ρ(o) is greater than ρ(f) then the weight will always be greater than the upthrust and the object will sink
What determines whether an objecy floats or sinks?
The balance of the weight and the upthrust of the object. If the weight exceeds the upthrust, the object will sink
What is the density of a material?
Its mass per unit volume
What is the unit of stress?
Nm⁻² or Pa
State the equation of Hooke’s Law.
F = kx
State the Stoke’s Law equation
F=6πrηv
F = viscous drag force
η = viscosity of the fluid
r = radius of sphere
v = velocity of sphere
What is required for Stoke’s Law to apply?
Laminar flow
What shaped objects does Stoke’s law apply to?
Small, spherical objects
What is the unit for density?
kgm⁻³
State the equation for stress?
Force / Cross-sectional area