Physics AS Level - Deformation of Solids

what is deformation caused by

a force

tensile forces...

act away from each other, object stretches and there is an increase in length (extension)

compressive forces...

act towards each other, object gets squashed and there is a decrease in length (compression)

when does a spring produce an extension

when a load is attached

hooke's law

the extension produced is proportional to the applied force (due to the load) as long as the limit of proportionality hasnt been reached

hooke's law formula form

f = kx

formula for calculating effective spring constants in series

1/kE = 1/k1 + 1/k2

formula for calculating effective spring constants in parallel

kE = k1 + k2

stress

the force applied per unit cross-sectional area

formula of stress

stress = force/cross sectional area

strain

fractional increase in original length of the wire

formula of strain

strain = x/l

unit of stress

pascal

unit of strain

non-existent

young modulus

ratio of stress to strain

formula of young modulus

young modulus = stress/strain

unit of young modulus

pascal

what is the gradient of a stress-strain graph

young modulus

what is the area under the curve of a stress-strain graph

work done per unit volume/energy stored per unit volume

elastic deformation

when deforming forces are removed, the spring returns to its original length

plastic deformation

when deforming forces are removed, the spring does not return to its original length

what is the gradient in a fofce-extension graph

spring constant

what is the area under the curve of a force-extension graph

work done/strain energy stored

strain energy

the potential energy stored in or work by an object when it is deformed elastically, so area under a force-extension graph

strain energy equation

SE=1/2kx^2, 1/2Fx