Back to 'Unit 2: Kinematics in a Straight Line'

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  • 2.1: Vectors, Scalars, and Coordinate Systems

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    A scalar physical quantity is a measurement of quantity that has a magnitude (amount), but not a direction. Examples of scalar quantities include mass and temperature; no direction is associated with these measurements. Distance is also a scalar quantity because it has no direction associated with it.

    A vector physical quantity is a measurement that has a magnitude (amount) and direction. Vectors are often depicted as an arrow. The length of the arrow shows the magnitude of the quantity, and the direction of the arrow shows the direction of the vector.

    For simple one-dimensional systems, a vector is often written as the magnitude with a (+) or (−) to indicate direction, with (+) going toward the right and (−) going toward the left. Displacement and velocity are examples of vector quantities. For example, 5.5 km/s east. This measurement shows the magnitude of the velocity (5.5 km/s), and the direction (east).