Equations of uniformly accelerated motion
3 marks · NormalA train increases its speed from 20 m/s to 50 m/s under uniform acceleration of 6 m/s². Calculate the distance over which this acceleration occurs.
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175 m (±2)
Must show: Correct rearrangement for s, Correct substitution and evaluation
Common mistakes: Mixing up initial and final speeds
Show mark scheme and worked solution
Marking points
M1 · 1 mark · Substitutes correct values into v^2 = u^2 + 2as.
M2 · 1 mark · Correctly rearranges for s. (follow-through)
A1 · 1 mark · Correct answer of 175 m (accept in range 174–176 m). (follow-through)
Worked solution
Use v^2 = u^2 + 2as, rearrange for s:
Substitute values: v = 50, u = 20, a = 6
So the train accelerates over 175 m.