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Glossary
Acceleration.The rate of change of velocity; the
slope of the tangent line on a v-t graph.
Attractive.Describes a force that tends to pull the
two participating objects together. Cf. repulsive,
oblique.
Center of mass.The balance point of an object.
Component.The part of a velocity, acceleration, or
force that is along one particular coordinate axis.
Displacement.(avoided in this book) A name for
the symbol
.
x .
Fluid.A gas or a liquid.
Fluid friction.A friction force in which at least one
of the object is is a fluid (i.e. either a gas or a
liquid).
Gravity.A general term for the phenomenon of
attraction between things having mass. The
attraction between our planet and a human-
sized object causes the object to fall.
Inertial frame.A frame of reference that is not
accelerating, one in which Newton’s first law is
true
Kinetic friction.A friction force between surfaces
that are slipping past each other.
Light.Anything that can travel from one place to
another through empty space and can influence
matter, but is not affected by gravity.
Magnitude.The “amount” associated with a vector;
the vector stripped of any information about its
direction.
Mass.A numerical measure of how difficult it is to
change an object’s motion.
Matter.Anything that is affected by gravity.
Mks system.The use of metric units based on the
meter, kilogram, and second. Example: meters
per second is the mks unit of speed, not cm/s or
km/hr.
Noninertial frame.An accelerating frame of
reference, in which Newton’s first law is violated
Nonuniform circular motion.Circular motion in
which the magnitude of the velocity vector
changes
Normal force.The force that keeps two objects from
occupying the same space.
Oblique.Describes a force that acts at some other angle,
one that is not a direct repulsion or attraction. Cf.
attractive, repulsive.
Operational definition.A definition that states what
operations should be carried out to measure the thing
being defined.
Parabola.The mathematical curve whose graph has y
proportional to x
2
.
direction. Cf. tangential.
Repulsive.Describes a force that tends to push the two
participating objects apart. Cf. attractive, oblique.
Scalar.A quantity that has no direction in space, only an
amount. Cf. vector.
Significant figures.Digits that contribute to the accuracy
of a measurement.
Speed.(avoided in this book) The absolute value of or, in
more then one dimension, the magnitude of the
velocity, i.e. the velocity stripped of any information
Spring constant.The constant of proportionality between
force and elongation of a spring or other object under
strain.
Static friction.A friction force between surfaces that are
not slipping past each other.
Système International.. Fancy name for the metric
system.
Tangential.Tangent to a curve. In circular motion, used
to mean tangent to the circle, perpendicular to the