Physics 1029A/B Study Guide - Final Guide: Elastic Energy, Mechanical Equilibrium, Stress (Mechanics)
26 Jan 2015
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Strain: force exerted per unit area of surface on an extended object, relative change in size of the object, dimensionless. Three types of deformation (strain: change in length stretching, change in angle of extended object twisting, change in volume compression or expansion. Each strain is caused by a different stress: tensile stress. Width and depth of object are reduced simultaneously. Object stretches to a certain length at which the restoring force within the object balances the external forces establishing new mechanical equilibrium. If strain and stress are proportional to each other. Proportionality factor y young"s modulus (unit pa) Elastic limit: large y = large force acting on piece of material leads to only a small length increase, for the strain, describes the strain threshold beyond which equations don"t apply, permanent plastic deformations occur. Newton"s second law of mechanics applies: f = m * a.
