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of mass Q Block
position 2 Energy Force Height of
"energy barrier" Fixed
pivot point Height of
center of mass
in position 2 Position 1 (a) Position 2
(b) FIGURE 2.3–2 The concept of activation energy. (a) When a block is “pushed over,” the height of its center of
gravity initially increases and then decreases to a ﬁnal value less than its initial value. The difference between the
maximum and initial heights represents the “energy barrier” to this process. (b) The more general concept of an
energy barrier of height Q is illustrated schematically. In moving from position 1 to position 2, the overall energy of the
system decreases, but energy in the amount Q must be “supplied” in order for the transition to occur. | v v pg029 [R] insulator.
phase from a supersaturated solid solution.
basal plane The top or bottom plane in
G1 7-27060 / IRWIN / Schaffer
pgm 1-14-98 plm 3-21-98 MP
amorphous material A material that lacks the
hexagonal crystals the basal plane is deﬁn
long-range order that is characteristic of a crystalline
placed on the six corners of hexagons. It i
solid. Amorphous materials are either rubbers or glasses.
anisotropic Having properties that vary withAtomic Scale Structures
basal slip Deformation that occurs on t
anodizing A process kinetic factors are surface of
rates is kinetics. In many cases, the by which the more importantathan the thermoof HCP crystals as a result of dislocation
dynamic factors. For example, ordinary window glassoxidea by an
component is converted into a hard is not thermodynamically stable
structure. An investigation of the kinetics of the problem, however, shows that at room
basis The number of atoms or ions on e
temperature the rate at which window glass moves toward the lowest-energy, or equiposition.
librium, state is such that glass can exist in itsof materialsform which
antiferromagnetic A class nonequilibrium in for thousands of years.
This example illustrates the important concept that a reacti...
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