Scalar and Vector Quantities in Physics

Jun 15, 2025

Overview

This lecture explains the difference between scalar and vector quantities in physics, provides examples of each, and shows how vectors are represented.

Scalar Quantities

  • Scalar quantities have magnitude (size) only and no direction.
  • Common scalar quantities include mass, temperature, speed, energy, distance, and time.
  • Distance is an example of a scalar; it tells how far but not the direction.

Vector Quantities

  • Vector quantities have both magnitude and direction.
  • Examples include displacement, weight, force, velocity, acceleration, and momentum.
  • Displacement is a vector; it states both how far (magnitude) and in which direction.

Representing Vectors

  • Vectors are represented by arrows.
  • The length of the arrow shows the magnitude of the vector.
  • The direction of the arrow indicates the direction of the vector.

Key Terms & Definitions

  • Scalar quantity — a physical measurement with magnitude only and no direction.
  • Vector quantity — a physical measurement with both magnitude and direction.
  • Magnitude — the size or quantity of a physical measurement.
  • Distance — the total length traveled, a scalar quantity.
  • Displacement — the straight-line distance from start to finish in a specified direction, a vector quantity.

Action Items / Next Steps

  • Practice questions on scalar and vector quantities in the recommended revision workbook.