**What appears below is an informal glossary
of terms used in a high school physics course. On the one hand,
you are not likely to be tested on your knowledge of these terms
(there will not be a question asking you to define these terms).
On the other hand, your intimate knowledge of these terms may
make a significant impact on your test scores.**

VECTOR- a physical quantity
that can only be defined completely by giving it a magnitude
(or size) and a spatial direction. Examples might include 5 m
due north, 3 m / s that-a-way, or 10 m/s/s downward. |

SCALAR - A physical quantity
the can be defined adequately by giving a magnitude (size) only.
Spatial direction is not required. Time is a scalar; so too is
work and energy and power. |

DISPLACEMENT- The straight line distance from point A to point
to a point B. A VECTOR QUANTITY measured in m and km mostly;
occasionally measured in feet or miles. Note that the displacement
on a running track from a starting point A and continuing one
lap around the track, ending at point B (which in this example
is on top of A) is ZERO. |

DISTANCE
TRAVELED - This is path length, a meander,
without regard to direction. DISTANCE TRAVELED is a SCALAR quantity
measured in m and km mostly; occasionally measured in feet or
miles. Note that the distance traveled on a running track from
a starting point A, and continuing one lap around the track,
ending at point B (which in this example is on top of A) is 400
m on a standard track |

TIME - operationally
defined as a sequence of events. A SCALAR quantity measured mostly
in seconds and hours |

SPEED - DISTANCE TRAVELED
divided by TIME. This is a measure of how fast an object is moving,
without regard to direction. SPEED is a SCALAR quantity and is
the magnitude portion of VELOCITY A speedometer measures speed.
Speed is measured in m / s, and km / hr and occasionally ft/s
and mi / hr |

VELOCITY - DISPLACEMENT
divided by TIME. VELOCITY is a VECTOR quantity.his is a measure
of how fast an object is moving, but noting both magnitude (how
big is it) as well as direction. VELOCITY is measured in m /
s, and km / hr and occasionally ft/s and mi / hr |

ACCELERATION - The change
in VELOCITY during a change in TIME. ACCELERATION is a VECTOR
quantity measured in m/s/s and km/hr/s and occasionally in ft/s/s
and mi/hr/s. |

Other velocities |

Initial
velocity - (a.k.a Vo )the velocity
of an object at the beginning of a trip. For an object launched
vertically, Vi is the velocity of the object immediately after
leaving the thrower's hand |

Final
velocity - The velocity of an object
at the end of a trip. For an object falling from a high place,
Vf is the velocity of the object just before it hits the ground. |

Average
speed - total distance traveled divided
by total elapsed time. |

Terminal
velocity - When an object is released
from a high place, gravity causes the object to accelerate downward.
As it accelerates, its velocity increases downward. Air resistance
causes the net downward acceleration to be diminished. until
it reaches Zero. After this moment in time, Fnet goes to Zero,
acceleration goes to zero. The object now falls at the same rate
the rest of the way down. This is known as terminal velocity;
for objects under the influence of the Earth's gravity and atmosphere,
terminal velocity is of the order of 54 m/s (= 176 ft/s or 120
mi/hr) |

**Forces**

Applied Force - ( a.k.a.
FA) A push or pull that can produce or prevent motion. |

Gravity (a.k.a. Fg) An intrinsic force wherin every object
with a mass shares a mutual attraction with every other object
with a mass. While wew are under the influence of gravitational
attraction from every other object in the universe, our immediate
neighborhood is dominated by the Earth's gravitational field.
The gravitational field intensity vector here on the Earth has
a numerical value of 9.8 m/s/s and is directed toward the center
of the planet. |

Normal Force (a.k.a FN).
When an object is placed on a surface, the force of gravity pulls
down on the object. For the object to remain in place, an upward
force, perpendicular to the surface and pointing away from the
surface, is supplied by the surface. When crossing a bridge.
the bridge holds if it can muster a sufficient upward force to
equalize gravity |

Frictional
Force (a.k.a.Ff) A contact for that
opposes or tends to oppose motion. We find that the ratio of
frictional force to the Normal force is a constany u. Otherwise,
Ff = u FN. The values of u are close to zero when therer is no
friction, higher values when friction comes into play |

Tension (a.k.a.
Ft). When a force is applied to an object by attaching a string
to it. Strings are intended to pull on objects rather than push
on them.. |

Centripetal
Force (from Latin centri- center;
peto retere to seek.) Consider a cart moving left to
right at constant speed. To make the object move faster, we push
to the right. To slow the object, we push to the left. If the
force is applied at right angles to the motion, the speed is
neither increased nor decreased. It is the DIRECTION that has
changes. If the direction of the applied force is change so as
to be alwaysa at right angles to the velocity vector, the path
is a circle. |

Centrifugal
force (from the Latin centri-
center; fugo, fugere to flee. Ostensibly, a force necessary
to keep an object moving in a circular path. Centrifugal force
does not exist and any evidence to the contrary can usually be
traced to a mis-application of Newton's first law of motion.
Yes, there exists a laboratory apparatus called a centrifuge.
So what? |