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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

.

Radial.Parallel to the radius of a circle; the in-out

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

about its direction

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

radial direction Cf. radial.

Uniform circular motion.Circular motion in which the

magnitude of the velocity vector remains constant

Vector.A quantity that has both an amount (magnitude)

and a direction in space. Cf. scalar.

Velocity.The rate of change of position; the slope of the

tangent line on an x-t graph.

Weight.The force of gravity on an object, equal to mg.