A student is sorting physical quantities into two groups: scalar quantities and vector quantities. The student places distance, speed, velocity, and acceleration into their groups. Describe the difference between a scalar quantity and a vector quantity, and for each of the four quantities listed, state whether it is a scalar or a vector, giving a reason for your answer for velocity.

Pearson Edexcel International GCSE Physics (4PH1) — 1.1 Units · Describe · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

A scalar quantity has only magnitude, no direction. A vector quantity has both magnitude and direction.

Distance – scalar, because it is a magnitude only.
Speed – scalar, because it is a magnitude only.
Velocity – vector, because it is speed in a given direction (e.g. 5 m s⁻¹ north).
Acceleration – vector, because it is a change in velocity, having both magnitude and direction.

Examiner tips

  • Use the definition of scalar/vector first. State each quantity’s type clearly. Give a short reason for velocity – mention direction.

Mark scheme (4 marks)

  1. A scalar quantity has magnitude only (and no direction) / a vector quantity has both magnitude and direction.
  2. Distance and speed are both scalar quantities.
  3. Velocity and acceleration are both vector quantities.
  4. Velocity is a vector because it is speed in a given direction / it has both magnitude and direction (e.g. 5 m/s north).

Key terms in this question

scalar quantity · vector quantity · velocity · acceleration

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