A cyclist sets off from rest and reaches a speed of 12 m/s in 8 seconds. She then travels at a constant speed for 30 seconds before slowing down uniformly and stopping in a further 6 seconds. Describe how the velocity and acceleration of the cyclist change during each of the three stages of the journey.

Eduqas GCSE Physics — 4.1 Speed, velocity and acceleration · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

Stage 1: velocity increases from 0 to 12 m s⁻¹; acceleration is positive.
Stage 2: velocity remains constant at 12 m s⁻¹; acceleration is zero.
Stage 3: velocity decreases from 12 to 0 m s⁻¹; acceleration is negative (opposite to motion).

Examiner tips

  • Use the word ‘increases’/‘decreases’ for velocity; state acceleration sign for each stage.
  • Mention ‘constant’ for stage 2 and ‘zero’ acceleration.
  • Show the direction of acceleration in stage 3 as opposite to motion.

Common mistakes

  • Confusing acceleration sign (writing positive for deceleration).
  • Forgetting to state that velocity is constant in stage 2.
  • Using ‘speed’ instead of ‘velocity’ in the description.

Mark scheme (4 marks)

  1. During the first stage, the velocity increases (from zero to 12 m/s) / the cyclist accelerates
  2. During the second stage, the velocity is constant / the acceleration is zero
  3. During the third stage, the velocity decreases (to zero) / the cyclist decelerates
  4. The acceleration in the third stage is in the opposite direction to the motion / the acceleration is negative (deceleration)

Key terms in this question

velocity · acceleration · constant speed

Related

More Speed, velocity and acceleration questions

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