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Unilorin Post-UTME Physics 2023 (Model questions) Question 9

Question 9

Equilibrium of Forces

A uniform metre rule of weight 1.0N is pivoted at the 40cm. A weight of 2.0N is hung at the 15cm mark. Where must a weight of 2N be placed to balance the rule?

  1. A.60cm
  2. B.45cm
  3. C.55cm
  4. D.35cm
Show the answer and explanation

Answer: A (60cm)

Explanation

Anticlockwise moment: 2 × (40 − 15) = 50. Clockwise: 1 × (50 − 40) + 2 × (x − 40) = 50, so 2(x − 40) = 40 and x = 60 cm.