What is a vector?

• A. A quantity that has magnitude only
• B. A quantity that has both magnitude and direction
• C. A type of scientific tool
• D. A measurement of speed only

Answer: (B)

A vector is defined as a quantity that possesses both magnitude and direction. This means that when describing a vector, you not only state how much (the magnitude) but also specify which way it is oriented (the direction). For example, if you say a car is moving at 60 kilometers per hour to the north, you are describing a vector because you have provided both the speed (magnitude) and the direction (north).

In contrast, other quantities that may seem similar do not include both elements. A quantity that has magnitude only, such as temperature or mass, does not provide directional information. Scientific tools do not define a vector, as they are instruments used for measurement rather than quantities. Lastly, a measurement of speed refers only to how fast something is moving, which is a scalar quantity, lacking directional information. Thus, the definition of a vector is accurately captured by the option that includes both magnitude and direction.