| Acceleration |
The rate of change with respect
to time of angular or linear velocity |
| Angular Momentum |
Defined as the Moment of
Inertia multiplied by the Angular Velocity. Any applied Torque
changes its value. |
| Bracing Height |
The distance from the bow
string to the plunger button or back of the bow. |
| Center
of Mass
(Gravity) |
The point at which the total
mass can assumed to be located with respect to linear motion.
e.g. the linear momentum of an arrow is the mass of the arrow
multiplied by the velocity of the Center of Mass. The Center of
Gravity (the balance point) is located at the Center of Mass. |
| Drag Force |
Defined as the rate of change
with time of Momentum of an object resulting from the
interaction with the air. The Total Drag Force on an object is
conventionally split between a component along the object's axis
(called drag) and a component at 90 degrees to this (called
lift). This convention is not very useful for describing drag
effects on an arrow and drag directions here are selected as
appropriate to a particular case. The most common directions
used are the vertical and horizontal components of the Total
Drag with respect to the archer-target. |
| Inertial Drag |
Drag Force resulting basically
from the arrow changing the direction of the air flow over it. |
| Kinetic Energy |
Energy related to motion.e.g.
linear kinetic energy is the half the mass times the square of
the velocity. |
| Linear Momentum |
Defines as the mass multiplied
by the velocity. Any applied force changes its value. |
| Momentum |
See Angular Momentum or Linear
Momentum |
| Munk Moment |
A torque produced on an arrow
resulting from aerodynamic effects at the rear (nock end) |
| Nock |
The fitting at the end of an
arrow shaft to locate the arrow on the string during the power
stroke. |
| Nodal Point |
A point in a vibrating system
where the displacement is zero for all time. |
| Offset Angle |
The angle between the axis of
the arrow shaft and the direction of travel of the arrow Center of Mass. One of the main determinants of the total Drag Force on
the arrow. |
| Pile |
The (usually metal) fitting at
the front of an arrow having a point for penetration and weight
for how the arrow shoots and flies. |
| Reynolds Number |
Defined as the ratio of
inertial to viscous forces in the fluid system. Its value
indicates whether the air flow is smooth or turbulent. |
| Rotation/Spinning |
The terms are used to mean
rotation around a point at 90 degrees to the arrow shaft
(fishtailing/porpoisng) or rotation around a point parallel to
the arrow shaft (e.g. using helical or spin wing type fletching). |
| Torque |
Defined as force multiplied by
distance to point of rotation. Changes the value of the Angular
Momentum. |
| Velocity |
Rate of change of position
(linear velocity) or angle (angular velocity) with time |
| Viscous Drag |
Drag Force resulting basically
from air friction. |
| Vortex Shedding |
Creation of eddies in a
systematic way in the wake behind a flying arrow |