Which physical quantity is a vector?

Force is a vector quantity because it has both magnitude and direction. In physics, a vector represents any quantity that requires both a size (how much) and a direction (which way) to fully describe it. For example, if one considers a force applied to an object, knowing just how strong that force is does not provide complete information; one must also know the direction in which the force is applied.

In contrast, mass, speed, and temperature are all scalar quantities. Mass is a measure of the amount of matter in an object and is described by its magnitude only, with no directional component. Speed measures how fast an object is moving without specifying the direction, making it a scalar too. Temperature, being a measure of thermal energy, is also solely dependent on magnitude and has no associated direction. Therefore, only force fits the definition of a vector quantity in this context.