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WAEC Further Mathematics 2012 Question 21

Question 21

Dynamics

A stone is dropped from a height of 45m. Find the time it takes to hit ground. [Take g = 10ms−2]

  1. A.3.0seconds
  2. B.4.5 seconds
  3. C.5.0 seconds
  4. D.9.0 seconds
Show the answer and explanation

Answer: A (3.0seconds)

Explanation

Dropped means u = 0, so 45 = ½ × 10 × t2, t2 = 9 and t = 3.0 s.