Zusammenfassung der Ressource
Solids
- Density
- Density= m/v
- ρ
- Mass per unit volume
- Springs
- Hooke's Law
- Extension applied is directly proportional to the load applied
- Providing the limit of proportionality is not
exceeded!
- ΔL ∝ F
- F=KΔL
- K= Spring constant in n/m
- Some materials do not obey, eg. rubber
- Young's Modulus
- Tensile Stress
- The perpendicular force applied per unit cross-sectional area
- Tensile Stress = F/A
- Pa or N/m^2
- Tensile Strain
- Extension produced per unit original length
- No units
- ΔL/L
- Ratio of tensile stress applied to tensile strain produced
- Pa or N/m^2
- E or Y
- Stress- Strain graph
- Gradient = E
- Area underneath = Strain energy per unit volume
- Force-Extension Graphs
- F= EA/L ΔL
- EA/l = gradient
- E = gradient * l / A
- Energy Stored
- Work Done = Force x Distance
- FΔs = Area under graph
- = 1/2 b x h
- = 1/2 ΔL x F
- = 1/2 F ΔL
- Energy Stored = Work Done
- 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