Technically, this model is applicable to a single point particle subject to a constant acceleration that is either parallel to or anti-parallel to the particle's initial velocity. Its real usefulness lies in the fact that it can describe mutli-dimensional motion with constant acceleration if the motion along different orthogonal directions is treated by application of the one-dimensional rules independently along the differect axes. Thus, it can be used describe the system's motion in any situation where the net force on the system is constant (a point particle subject only to near-earth [gravitation] is a common example). It is a subclass of the One-Dimensional Motion (General) model defined by the constraint da/dt = 0.

For pure kinematics situations, the problem will often explicitly state that the acceleration is constant, or else will indicate this bu giving some quantitative information that implies the acceleration is constant (e.g. a linear plot of velocity versus time). This model is always applicable to the vertical direction in a problem that specified gravitational freefall. The model is also sometimes useful (in conjunction with Point Particle Dynamics) in dynamics problems when it is clear that the net force is constant.

• 1-D Motion (Constant Velocity)

• [position (one-dimensional)]
• velocity
• acceleration

A single point particle (or a system treated as a point particle with position specified by the center of mass).

Some constant external influence must be present which produces a constant acceleration that is directed parallel or anti-parallel to the particle's initial velocity.

This model has several mathematical realizations that involve different combinations of the variables.

• Position as a Function of Time
  From the formulas given in the Laws of Change, it is clear that a plot of position vs. time will give a parabola. If the acceleration is positive the parabola will open upwards, and have a minimum value at the time

• Velocity versus time graph.