Physics
Give the (Hooke's Law) formula for force
F = Kx
K - Spring Constant
x = extension
How can you find elastic potential energy(Elastic stain energy) on a force extenstion graph
By finding the area underneath the graph
Give the formula for EPE
1/2Kx^2
K - spring constant
e^2 is extension squared
Define 'tensile stress'
The force applied per unit area of cross section when a material is stretched
Give the formula for tensile stress
Force / Cross-sectional area
Define 'tensile strain'
The fractional change in length to the original length
Give the formula for tensile strain
Extension(m) / Original Length(m)
What's Young's modulus equation
Tensile Stress/Tensile Strain
Define 'Tensile' forces
Forces that are applied if something is being stretched or extended
Define 'Compressive Forces'
Forces that are applied when something is being squashed or compressed
What is young's modulus
The stiffness of a material being stressed
Define 'Ultimate Tensile Strength'
The stress value of which a material breaks
Give some features of the force extenstion graph of rubber
- Doesn't experience plastic deformation
- It forms a hysteris loop, which the area in between represents the thermal energy released when loading and unloading
- It doesn't obey hookes law
Give some features of the force extenstion graph of a metal wire
- Obeys hookes law and shows elastic deformation up until the elastic limit
-Beyond the elastic limit it experiences plastic deformation
Give some features of the stress-strain graph of brittle materials
- Shows elastic behaviour until breakpoint, where the material shatters
- There's no plastic deformation
-Loading and unloading are on the same curve
Give some features of the stress-strain graph of rubber materials
- Has no plastic deformation
- Loading and unloading curve is different as thermal energy is lost
- Has a high tensile stress
Give some features of the stress-strain graph of ductile materials
- Experiences elastic deformation as until its elastic limit, then experiences plastic deformation before reaching its UTS and breakpoint
How do we find force constant when springs are in series
1/kTOTAL = 1/k1 +1/k2 etc
How do we find force constant when springs are in parallel
kTOTAL = k1 + k2 etc
Give some features of the force extenstion graph of polythene
- Doesn't obey hookes law
- Shows plastic deformation when any force is applied to it
- Easy to stretch