释义 |
AccelerationLet a particle travel a distance as a function of time (here, can be thought of as the ArcLength of the curve traced out by the particle). The Speed (the Scalar Norm of the Vector Velocity) is then given by
 | (1) |
The acceleration is defined as the time Derivative of the Velocity, so the Scalar acceleration isgiven by
The Vector acceleration is given by
 | (7) |
where is the Unit Tangent Vector, the Curvature, the Arc Length, and the Unit Normal Vector.
Let a particle move along a straight Line so that the positions at times , , and are , ,and , respectively. Then the particle is uniformly accelerated with acceleration Iff
 | (8) |
is a constant (Klamkin 1995, 1996).
Consider the measurement of acceleration in a rotating reference frame. Apply the Rotation Operator
 | (9) |
twice to the Radius Vector r and suppress the body notation,
Grouping terms and using the definitions of the Velocity and AngularVelocity give the expression
 | (11) |
Now, we can identify the expression as consisting of three terms
a ``body'' acceleration, centrifugal acceleration, andCoriolis acceleration. Using these definitions finally gives
 | (15) |
where the fourth term will vanish in a uniformly rotating frame of reference (i.e., ). Thecentrifugal acceleration is familiar to riders of merry-go-rounds, and theCoriolis acceleration is responsible for the motions of hurricanes onEarth and necessitates large trajectory corrections for intercontinental ballistic missiles.See also Angular Acceleration, Arc Length, Jerk, Velocity References
Klamkin, M. S. ``Problem 1481.'' Math. Mag. 68, 307, 1995. Klamkin, M. S. ``A Characteristic of Constant Acceleration.'' Solution to Problem 1481. Math. Mag. 69, 308, 1996. |