WGU PHYSICS
# Term Definition
1 Angular momentum Back (Definition)
2 Tangential speed The linear speed tangent to a curved path, such
as in circular motion.
3 Rotational speed The number of rotations or revolutions per unit
of time; often measured in rotations or
revolutions per second or per minute. (Scientists
usually measure it in radians per second.)
4 Rotational inertia That property of an object that measures its
resistance to any change in its state of rotation:
if at rest, the body tends to remain at rest; if
rotating, it tends to remain rotating and will
continue to do so unless acted upon by an
external net torque.
5 Torque Torque The product of force and lever-arm
distance, which tends to produce rotation.
Torque = lever arm × force
6 Center of mass (CM) The average position of the mass of an object.
The CM moves as if all the external forces acted
at this point.
7 Center of gravity (CG) The average position of weight or the single
point associated with an object where the force
of gravity can be considered to act.
8 Equilibrium The state of an object in which it is not acted
upon by a net force or a net torque.
9 Centripetal force A force directed toward a fixed point,usually the
cause of circular motion: F = mv2/r
,WGU PHYSICS
# Term Definition
10 Centrifugal force An outward force apparent in a rotating frame
of reference. It is apparent (fictitious) in the
sense that it is not part of an interaction but is a
result of rotation—with no reaction-force
counterpart.
11 Angular momentum The product of a body’s rotational inertia and
rotational velocity about a particular axis. For an
object that is small compared with the radial
distance, it can be expressed as the product of
mass, speed, and the radial distance of rotation.
12 Conservation of angular When no external torque acts on an object or a
momentum system of objects, no change of angular
momentum can occur. Hence, the angular
momentum before an event involving only
internal torques or no torques is equal to the
angular momentum after the event.
13 Law of universal gravitation Law of universal gravitation Every body in the
universe attracts every other body with a force
that, for two bodies, is directly proportional to
the product of their masses and inversely
proportional to the square of the distance
separating them: F equals G m sub 1 m sub 2
over d to the 2 power
14 Ellipse The oval path followed by a satellite. The sum of
the distances from any point on the path to two
points called foci is a constant. When the foci
are together at one point, the ellipse is a circle.
As the foci get farther apart, the ellipse
becomes more “eccentric.
15 Kepler’s laws Kepler’s laws Law 1: The path of each planet
around the Sun is an ellipse with the Sun at one
focus. Law 2: The line from the Sun to any
planet sweeps out equal areas of space in equal
time intervals. Law 3: The square of the orbital
period of a planet is directly proportional to the
cube of the average distance of the planet from
the Sun (T2 r3 for all planets).
16 Escape speed Escape speed The speed that a projectile, space
probe, or similar object must reach to escape
the gravitational influence of Earth or of
another celestial body to which it is attracted.
, WGU PHYSICS
# Term Definition
17 Electricity Electricity General term for electrical
phenomena, much like gravity has to do with
gravitational phenomena, or sociology with
social phenomena.
18 Electrostatics Electrostatics The study of electric charge at rest
(not in motion, as in electric currents).
19 Conservation of charge Electric charge is neither created nor destroyed.
The total charge before an interaction equals
the total charge after.
20 Coulomb’s law Coulomb’s law The relationship between
electrical force, charge, and distance: F equals k
q sub 1 q sub 2 over d to the 2 power
21 Coulomb Coulomb The SI unit of electrical charge. One
coulomb (symbol C) is equal to the total charge
of 6.25 × 1018 electrons.
22 Conductor Conductor Any material having free charged
particles that easily flow through it when an
electric force acts on them
23 Insulator Insulator A material without free charged
particles and through which charge does not
easily flow.
24 Inverse-square law A law relating the intensity of an effect to the
inverse square of the distance from the cause.
Gravity follows an inverse-square law, as do the
effects of electric, magnetic, light, sound, and
radiation phenomena.
25 Semiconductor Semiconductor A material with properties that
fall between a conductor and an insulator and
whose resistance can be affected by adding
impurities.
26 Superconductor Superconductor A material that is a perfect
conductor with zero resistance to the flow of
electric charge.
# Term Definition
1 Angular momentum Back (Definition)
2 Tangential speed The linear speed tangent to a curved path, such
as in circular motion.
3 Rotational speed The number of rotations or revolutions per unit
of time; often measured in rotations or
revolutions per second or per minute. (Scientists
usually measure it in radians per second.)
4 Rotational inertia That property of an object that measures its
resistance to any change in its state of rotation:
if at rest, the body tends to remain at rest; if
rotating, it tends to remain rotating and will
continue to do so unless acted upon by an
external net torque.
5 Torque Torque The product of force and lever-arm
distance, which tends to produce rotation.
Torque = lever arm × force
6 Center of mass (CM) The average position of the mass of an object.
The CM moves as if all the external forces acted
at this point.
7 Center of gravity (CG) The average position of weight or the single
point associated with an object where the force
of gravity can be considered to act.
8 Equilibrium The state of an object in which it is not acted
upon by a net force or a net torque.
9 Centripetal force A force directed toward a fixed point,usually the
cause of circular motion: F = mv2/r
,WGU PHYSICS
# Term Definition
10 Centrifugal force An outward force apparent in a rotating frame
of reference. It is apparent (fictitious) in the
sense that it is not part of an interaction but is a
result of rotation—with no reaction-force
counterpart.
11 Angular momentum The product of a body’s rotational inertia and
rotational velocity about a particular axis. For an
object that is small compared with the radial
distance, it can be expressed as the product of
mass, speed, and the radial distance of rotation.
12 Conservation of angular When no external torque acts on an object or a
momentum system of objects, no change of angular
momentum can occur. Hence, the angular
momentum before an event involving only
internal torques or no torques is equal to the
angular momentum after the event.
13 Law of universal gravitation Law of universal gravitation Every body in the
universe attracts every other body with a force
that, for two bodies, is directly proportional to
the product of their masses and inversely
proportional to the square of the distance
separating them: F equals G m sub 1 m sub 2
over d to the 2 power
14 Ellipse The oval path followed by a satellite. The sum of
the distances from any point on the path to two
points called foci is a constant. When the foci
are together at one point, the ellipse is a circle.
As the foci get farther apart, the ellipse
becomes more “eccentric.
15 Kepler’s laws Kepler’s laws Law 1: The path of each planet
around the Sun is an ellipse with the Sun at one
focus. Law 2: The line from the Sun to any
planet sweeps out equal areas of space in equal
time intervals. Law 3: The square of the orbital
period of a planet is directly proportional to the
cube of the average distance of the planet from
the Sun (T2 r3 for all planets).
16 Escape speed Escape speed The speed that a projectile, space
probe, or similar object must reach to escape
the gravitational influence of Earth or of
another celestial body to which it is attracted.
, WGU PHYSICS
# Term Definition
17 Electricity Electricity General term for electrical
phenomena, much like gravity has to do with
gravitational phenomena, or sociology with
social phenomena.
18 Electrostatics Electrostatics The study of electric charge at rest
(not in motion, as in electric currents).
19 Conservation of charge Electric charge is neither created nor destroyed.
The total charge before an interaction equals
the total charge after.
20 Coulomb’s law Coulomb’s law The relationship between
electrical force, charge, and distance: F equals k
q sub 1 q sub 2 over d to the 2 power
21 Coulomb Coulomb The SI unit of electrical charge. One
coulomb (symbol C) is equal to the total charge
of 6.25 × 1018 electrons.
22 Conductor Conductor Any material having free charged
particles that easily flow through it when an
electric force acts on them
23 Insulator Insulator A material without free charged
particles and through which charge does not
easily flow.
24 Inverse-square law A law relating the intensity of an effect to the
inverse square of the distance from the cause.
Gravity follows an inverse-square law, as do the
effects of electric, magnetic, light, sound, and
radiation phenomena.
25 Semiconductor Semiconductor A material with properties that
fall between a conductor and an insulator and
whose resistance can be affected by adding
impurities.
26 Superconductor Superconductor A material that is a perfect
conductor with zero resistance to the flow of
electric charge.
