Question

Differentiate between a scalar and a vector quantity.

Answer 1

Hint: A scalar quantity is any physical quantity that has only magnitude but no direction. A vector quantity has both magnitude and a specific direction. Therefore, in essence, a scalar quantity is nothing but a vector quantity with no specified direction.

Complete step by step answer:
In the world of physics, physical quantities are grouped into either scalar quantities or vector quantities.
Scalar quantities are physical quantities that have only a magnitude but no direction. Hence, scalar quantities can be added algebraically like integers. For example, mass is a scalar quantity.
Vector quantities are physical quantities that have both magnitude and direction. That is they are similar to scalar quantities in the sense that they have a specific magnitude, however unlike scalars they have a direction. That is the physical effect of the vector is visible in a specific direction.
For example, force is a vector quantity. This is because only the magnitude of force does not tell the complete story and effect of the force but also the direction in which the force is applied plays an important part.
Vectors cannot be added algebraically like scalar quantities. They have specific laws for their addition, known as the vector laws of addition, which is quite different from algebraic addition. Vector addition also considers the effect of the direction of the vector in the addition process.

Note: Sometimes some physical quantities may behave like vectors but are actually not. For example, in AC circuits, physical quantities like current are represented as phasors. Phasors follow the vector laws of addition, however they cannot be considered as vectors, since they do not have direction.
Therefore, students must not get confused between phasors and vectors.