Scalar and Vector Quantities

Scalar Quantities

Scalar quantities are physical quantities that have a magnitude but no direction. They are measured with a numerical value. Some examples of scalar quantities are:

  • Distance – E.g. 10 metres (m)
  • Mass – E.g. 14 kilograms (kg)
  • Speed – E.g. 42 metres per second (m/s)
  • Density – E.g. 2,400 kilograms per metre cubed (kg/m³)
  • Temperature – E.g. 9 degrees (°C)
  • Time – E.g. 4 PM (16:00)

Vector Quantities

Vector quantities are different from scalar quantities because they have both magnitude and direction. Some examples of vector quantities are:

  • Acceleration – E.g. 5 metres per second (m/s) north
  • Displacement – E.g. 40 kilometres (km) west
  • Force – E.g. 50 newtons (N) upwards
  • Momentum – E.g. 100 kilogram metres per second (kg m/s) south
  • Velocity – E.g. 5 metres per second (m/s) upwards

Instead of a written description, arrows can be used to represent vectors. The arrow indicates both the magnitude and the direction.

For example, an arrow pointing to the right with a label ’20N’ would mean a force of 20 newtons to the right.