Solids - created from Mind Map

Seite 1

Density

Density= m/v

ρ

Mass per unit volume

Springs

Hooke's Law

Extension applied is directly proportional to the load applied

Some materials do not obey, eg. rubber

Providing the limit of proportionality is not exceeded!

ΔL ∝ F

F=KΔL

K= Spring constant in n/m

Young's Modulus

Tensile Stress

Tensile Strain

Ratio of tensile stress applied to tensile strain produced

Pa or N/m^2

E or Y

Stress- Strain graph

The perpendicular force applied per unit cross-sectional area

Tensile Stress = F/A

Pa or N/m^2

Extension produced per unit original length

No units

ΔL/L

Gradient = E

Area underneath = Strain energy per unit volume

Force-Extension Graphs

F= EA/L ΔL

Energy Stored

EA/l = gradient

E = gradient * l / A

Work Done = Force x Distance

1/2 F ΔL

FΔs = Area under graph

Energy Stored = Work Done

= 1/2 b x h

= 1/2 ΔL x F

= 1/2 F ΔL

Key Terms

Limit of proportionality- The point beyond which Hooke's law is no longer obeyed

Elastic behaviour- Original size & shape is regained after force is removed

Plastic Behaviour- Some permanent deformation when force is removed

Elastic Limit - The maximum amount of stretch whilst still regaining original size and shape when force removed

Yield Point- The point at which the material 'gives' a little. There is a marked increase in extension due to crystal planes sliding across eachother

Ultimate Tensile Strength - The maximum tensile stress that can be applied to a material without it breaking

Stiff - Very little deformation when a force is applied

Brittle - Very stiff and breaks with hardly any plastic deformation

Fracture - Cracks appear on the surface of the solid when a force is applied causing it to break

Ductile - Shows plastic deformation

Solids