Difference Between Scalar Quantity and Vector Quantity

Scalar Quantity vs Vector Quantity

Math and physics are two subject invented by us to describe various phenomenon around us. This fits perfectly upon quantities that are measured using math and physics. Scalar and vector are classification of quantities in physics. There are some quantities that have only one dimension that is a number assigned to them whereas there are others that have also a dimension of direction assigned to them. Examples of first type are length, area, pressure, temperature, energy, work, and power whereas examples of the type that require direction to be mentioned are velocity, displacement, acceleration, momentum, force etc. There is difference between these two types of quantities that will be discussed in this article.

The most basic difference, which is also the only difference between scalar and vector quantities, is that scalar quantities have only magnitude whereas vector quantities have magnitude as well as direction associated with them. Let us understand this with the help of a few examples.

If you are describing the area of a room, you do not need to tell its direction, do you? It looks absurd to be talking in terms of direction of the area of a room. But yes, there are concepts that require direction and without the mention of direction, they are meaningless, such as velocity, and displacement. If a boy is running on a circular track of circumference 500 meters, you are right is saying that he covered a distance of 500 meters when he completes one circle. But since he comes back to the starting point, he has not registered any displacement. The same can be said about a stone that is thrown up straight in the skies and comes back to its starting point. There is no displacement though it has covered a sizeable distance in its journey.

If you talk about the volume of a glass, you don’t need to specify its direction, but what will you do if you are asked about the location of the glass? Direction enables us to find out where the glass is. One quantity that is a vector quantity is the velocity of a moving object. Though you can get away when you say that the speed of the moving car is 50mph, the same cannot be said when you are talking in terms of its velocity. Velocity needs direction, and hence you have to include it when describing velocity. So you have to say that the car has a velocity of 50mph in north direction. The concept of velocity is an extremely important one as it leads to understanding of acceleration, the basic of understanding the motion of our planets, aircrafts and spacecrafts.