What is Velocity?

If you have been to a physics class you may already know the answer to the question, what is velocity? There are however those who may have been away when this topic was introduced to the class as well as some who may have forgotten the lesson. For the benefit of all of us who may be in either of these categories we shall once more look at what is velocity and get to know some more about the term.

Velocity is defined as the rate of change in position in a specific direction. These are the three components of velocity, rate of change, change in position and direction. The rate of change in position of an object is actually the speed. We can therefore say that velocity is speed in a particular direction. Any activity lacking one of the two components will always result in zero velocity. Due to the direction component of velocity it is considered a vector quantity. These are quantities that have magnitude as well as direction; acceleration and weight are other examples of vector quantities.

When expressing velocity it incorporates both components of speed and direction and is displayed as meters per seconds in a direction. An example is 5m/s, West. An object traveling at a constant velocity is one that maintains speed and direction. A change in either will result in a change in the velocity. Speed does not factor directions and is a scalar quantity. Another way to put this is that velocity is displacement within a particular time. Displacement is distance in a particular direction and you will therefore have velocity as distance covered in a particular direction within a specified time. This is actually a better description as the use of speed can at times confuse those who are not very conversant with velocity.

There are three types of velocity that are usually encountered when working on various projects. The first type is the instantaneous velocity which considers velocity at a single point or a particular time during motion. The instantaneous velocity will vary from point to point or time to time unless the object is able to maintain a constant speed and direction throughout. Calculating instantaneous velocity is a bit more involving as compared to the other types of velocity. We also have average velocity which factors the entire distance of motion and the time of the entire motion in a particular direction. Average speed is calculated by dividing the distance by the time taken in a certain direction. Finally we have relative motion which compares velocity of one object with that of another that is moving on it. To calculate relative velocity requires you add the velocities of both objects.

Though there is often confusion between speed and velocity, the above information clearly demonstrates that the two are different with one being a scalar quantity while the other is a vector quantity. Hopefully this has served as a refresher for those who may have forgotten the lesson on velocity.