One-Dimensional Motion with Constant Velocity
Description and Assumptions
This model is applicable to a single point particle moving with constant velocity, i.e. with no net force. It is a subclass of the One-Dimensional Motion with Constant Acceleration model defined by the constraint a = 0.
Problem Cues
For pure kinematics problems, the problem will often explicitly state that the velocity is constant, or else some quantitative information will be given (e.g. a linear position versus time plot) that implies the velocity is constant. Alternatively, there may be no net force on the particle, e.g. if it slides on ice or on wheels.
Learning Objectives
Students will be assumed to understand this model who can:
- Describe the difference between distance and displacement.
- Define average velocity and average speed.
- Describe the features of a motion diagram that exhibits motion with constant velocity.
- Relate displacement, time and velocity.
- Find velocity from the slope of a position versus time graph.
- Describe the properties of the position versus time graph given the velocity and the initial position for a trip made at constant velocity.
- Mathematically determine when two objects moving with constant velocity will meet by constructing and solving a system of equations.
- Graphically determine when two objects moving with constant velocity will meet.
Model
System
A single point particle (or a system treated as a point particle with position specified by the center of mass).
Interactions
In order for the velocity to be constant, the system must be subject to no net force.
Law of Change
\begin
$x = x_
+ v (t - t_
)$\end
Diagrammatic Representations
- motion diagram
- position versus time graph
- [velocity versus time graph]