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WAEC Further Mathematics 2024 Question 28

Question 28

Dynamics

A body of mass 80 kg moving with a velocity of 25 ms−1 collides with another body moving in the opposite direction at 10 ms−1. After collision, both bodies moved with a common velocity of 12.8 ms−1. Calculate, correct to the nearest whole number, the mass of the second body.

  1. A.33 kg
  2. B.38 kg
  3. C.43 kg
  4. D.47 kg
Show the answer and explanation

Answer: C (43 kg)

Explanation

Momentum: 80(25) + m(−10) = (80 + m)(12.8). So 2000 − 10m = 1024 + 12.8m, 976 = 22.8m and m ≈ 43 kg.