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JAMB Physics 2013 Question 7

Question 7

Newton's Laws and Momentum

Calculate the apparent weight loss of a man weighing 70kg in an elevator moving downwards with an acceleration of 1.5ms−2. [g = 10ms−2]

  1. A.686N.
  2. B.595N.
  3. C.581N.
  4. D.105N.
Show the answer and explanation

Answer: D (105N.)

Explanation

Apparent weight = m(g − a) = 70 × 8.5 = 595 N, compared with a true weight of 700 N. The loss is ma = 70 × 1.5 = 105 N.