ABSTRACT
At the end of this chapter you should be able to:
• define force and state its unit • recognise a tensile force and state relevant
practical examples • recognise a compressive force and state
relevant practical examples • recognise a shear force and state relevant
practical examples • define stress and state its unit • calculate stress σ from σ = F
A
• define strain • calculate strain ε from ε = x
L
• define elasticity, plasticity, limit of proportionality and elastic limit
• state Hooke’s law • define Young’s modulus of elasticity E
and stiffness • appreciate typical values for E • calculate E from E = σ
ε
• perform calculations using Hooke’s law • plot a load/extension graph from given
data • define ductility, brittleness and malleabil-
ity, with examples of each • define rigidity or shear modulus • understand thermal stresses and strains • calculates stresses in compound bars
A force exerted on a body can cause a change in either the shape or the motion of the body. The unit of force is the newton, N.
