One Dimensional Motion

Motion involves an object moving from one place to another. This change in position is defined as the displacement of an object. It is given by the final position minus the intial position. A vector quantity is characterized as a magnitude and direction, but a scalar quantity has only magnitude.


Velocity is defined as the rate of change in an object's position. That is to say that it is a measurement of how quickly an object is moving. The standard unit for velocity is meters per second.

As velocity is a vector quantity, its value also includes a direction of motion. In one-dimensional motion, this direction is often easily accounted for by giving the value either a positive or negative sign. The term velocity is often used interchangeably with speed; however, students should be careful not to confuse the two. Speed does not include a direction, and is the magnitude of an object's velocity. In 1D motion, this is equivalent to the absolute value of velocity.

Under constant acceleration, an object's final velocity can be found by multiplying the acceleration by time and adding the result to the initial velocity. It is important to note that this only applies under conditions of constant acceleration. In order to find the change in velocity under changing acceleration, principles of calculus must be applied.

The average velocity is the change in location (displacement) divided by the change in time.
The average speed can be found by dividing the total distance with the total time.


Just as velocity is the rate of change in an object's position, acceleration is the rate of change in an object's velocity. In other words, it is a measurement of how quickly an object is changing speed or direction. It is a vector quantity, and as such has both a magnitude and a direction. In 1 dimensional motion, the direction can again be denoted by the presence of a positive or negative sign.


Acceleration - Rate of change in velocity measured in meters per second per second.
Free falling object - Any object moving freely under the influence of gravity alone, regardless of its initial motion
Velocity - Rate of change in distance measured in meters per second
Distance - The total length of the path traveled
Displacement - The final straight line distance from the starting point
Terminal Velocity- The maximum velocity an object can reach due to the affects of drag.