What defines a vector quantity?

A vector quantity is defined by having both magnitude and direction. This means that whenever you describe a vector quantity, you not only specify how much of that quantity there is (the magnitude) but also the direction in which it acts. For example, in physics, force is a classic vector quantity; if you say that a force of 10 Newtons is acting to the east, you are providing both the magnitude (10 Newtons) and the direction (east).

This characteristic distinguishes vector quantities from scalar quantities, which only have magnitude and do not involve direction. For instance, temperature is a scalar quantity since it can be described simply by a numerical value without any directional component.

By recognizing that force, displacement, velocity, and acceleration are all vector quantities, it becomes clear why specifying both magnitude and direction is essential for understanding their complete effect in physical systems.