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WAEC Further Mathematics 2021 Question 22

Question 22

Dynamics

A stone is thrown vertically upwards and its distance, S metres, after t seconds is given by S = 12t + (5/2)t2 − t3. Calculate the distance travelled in the third second

  1. A.5.5 m
  2. B.14.5 m
  3. C.26.0 m
  4. D.30.0 m
Show the answer and explanation

Answer: A (5.5 m)

Explanation

The third second is from t = 2 to t = 3: S(3) − S(2) = 31.5 − (24 + 10 − 8) = 5.5 m (the stone is still rising).