A sprinter runs a 100 m race along a straight track. At the starting gun the sprinter accelerates from rest, reaching a maximum velocity after 6 seconds. For the remainder of the race the sprinter moves at this constant maximum velocity. Describe what a velocity-time graph of the entire race would look like, and state what feature of the graph could be used to find the total distance covered during the race.

Pearson Edexcel International GCSE Physics (4PH1) — 1.2 Movement and position · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

The graph starts at the origin (t=0, v=0). From t=0 to t=6 s it is a straight line rising with a positive gradient, representing uniform acceleration to the maximum velocity. From t=6 s to the end of the race it is a horizontal straight line at that maximum velocity, showing constant speed. The total distance travelled is the area under the whole curve, i.e. the area between the line and the time axis.

Examiner tips

  • Show the two distinct straight‑line sections clearly labelled with time and velocity axes.
  • Mention that the area under the curve gives the displacement (distance).
  • Use correct units (m/s for velocity, s for time).

Common mistakes

  • Drawing a curved acceleration phase instead of a straight line.
  • Failing to label the horizontal section as constant velocity.
  • Not recognising that the area under the graph equals the distance travelled.

Mark scheme (4 marks)

  1. The graph starts at the origin / velocity is zero at time zero
  2. A straight line with a positive gradient from the origin up to the maximum velocity, lasting 6 seconds (first phase is uniform/constant acceleration)
  3. A horizontal straight line at the maximum velocity for the rest of the race (constant velocity phase)
  4. The area under the line / area between the line and the time axis gives the total distance travelled

Key terms in this question

velocity-time graph · distance

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