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WAEC Further Mathematics 2022 Question 27

Question 27

Dynamics

A body of mass 18 kg moving with velocity 4 ms−1 collides with another body of mass 6 kg moving in the opposite direction with velocity 10 ms−1. If they stick together after collision, find their common velocity.

  1. A.−½ ms−1
  2. B.⅓ ms−1
  3. C.2 ms−1
  4. D.3 ms−1
Show the answer and explanation

Answer: A (−½ ms−1)

Explanation

Taking the 6 kg body's direction as positive: 18(−4) + 6(10) = 24v, so v = −12/24 = −½ ms⁻¹ (0.5 ms⁻¹ in the direction the 18 kg body was moving).