A marble is released from rest at the top of a long, straight ramp and rolls to the bottom. Describe how the displacement-time graph for the marble's motion along the ramp would appear, and explain what each feature of the graph tells you about the marble's motion.

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).

A marble is released from rest and rolls down a straight ramp, increasing in speed until it reaches the bottom.

Model answer (4 marks)

The graph starts at the origin, showing zero displacement at zero time.
The line is curved, not straight, indicating that the velocity is changing.
The gradient of the curve increases with time, showing that the marble’s velocity is increasing – it is accelerating.
The gradient at any point on the curve equals the instantaneous velocity of the marble at that instant.

Examiner tips

  • Use the word ‘curved’ to show changing velocity. Show that the gradient increases to demonstrate acceleration. Explain that the gradient equals instantaneous velocity. Mention the origin to cover the start point.

Common mistakes

  • Writing a straight line, implying constant velocity. Forgetting to mention the origin. Confusing gradient with acceleration instead of velocity.

Mark scheme (4 marks)

  1. The graph starts at the origin (zero displacement at zero time).
  2. The line is curved (not straight), showing that velocity is changing.
  3. The gradient of the graph increases over time, showing that the marble's velocity is increasing (it is accelerating).
  4. The gradient at any point on the graph equals the instantaneous velocity of the marble at that moment.

Key terms in this question

displacement-time graph

Related

More Movement and position questions

▶ Try answering this question with AI marking (free) →