Question

State whether ‘Pressure’ is a scalar or vector?

Answer 1

Hint:Use the concept of Pascal’s law applied to the enclosed liquids. This law gives the relation between the pressure applied on a liquid enclosed in a container and direction of this pressure. Using this concept if pressure has direction then it will be a vector physical quantity and if pressure does not have direction then it will be a scalar physical quantity.

Complete answer:
Any physical quantity which has only magnitude and not a direction is known as a scalar physical quantity. The physical quantity having magnitude as well as direction is known as vector physical quantity.

According to Pascal’s law, when a pressure is exerted on a liquid enclosed in any container or compact structure, then this pressure will be experienced equally by every atom of the liquid at any place in the container and the walls of the container.

Hence, an atom of the liquid anywhere in the liquid will experience the same pressure from all sides. Thus, one cannot determine the exact direction of the pressure. The physical quantity having its magnitude uniform and acting in all directions is considered a scalar quantity which is the same case for pressure.

Hence, pressure is a scalar physical quantity.

Note:The students may think that pressure is defined as force per unit area and force is a vector quantity. Hence, pressure must be a vector quantity. But the actual formula of pressure is magnitude of force divided by the magnitude of area. Hence, pressure is a scalar quantity and not a vector quantity.