AFOQT Practice Test

What is the definition of a scalar quantity?

1. A physical quantity that has both magnitude and direction

2. A physical quantity that has quantity but no direction

3. A vector quantity that measures distance

4. A unit of measurement independent of dimensions

The correct answer is: A physical quantity that has quantity but no direction

A scalar quantity is defined as a physical quantity that has magnitude but no specific direction. This means that scalars are completely described by their size or amount. Examples of scalar quantities include mass, temperature, volume, and speed. In contrast, physical quantities that have both magnitude and direction are referred to as vector quantities. For example, velocity and force are vectors, as they indicate both how much there is (magnitude) and in what direction it acts. The other options refer to different types of measurements. The mention of a vector quantity measuring distance is inherently contradictory because distance is a scalar, while displacement is the vector quantity concerned with how far out of place an object is. Additionally, a unit of measurement independent of dimensions doesn’t properly represent the nature of scalar quantities, as scalars are defined by their magnitude without a directional component rather than being dimensionless.