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JAMB Physics 2005 Question 28

Question 28

Motion

A motorcyclist travelling at 30 ms−1 starts to apply his brakes when he is 50 m from the traffic light that has just turned red. If he just reached the traffic light, his deceleration is

  1. A.5 ms−2
  2. B.9 ms−2.
  3. C.10 ms−2.
  4. D.18 ms−2.
Show the answer and explanation

Answer: B (9 ms−2.)

Explanation

v2 = u2 − 2as: 0 = 900 − 100a, so a = 9 m s−2.