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JAMB Physics 1997 Question 15

Question 15

Elasticity

A load of 20 N on a wire of cross-sectional area 8 × 10−7 m2, produces an extension of 10−4 m. Calculate Young's modulus for the material of the wire if its length is 3 m.

  1. A.7.0 × 1011 N m−2
  2. B.7.5 × 1011 N m−2
  3. C.8.5 × 1011 N m−2
  4. D.9.0 × 1011 N m−2
Show the answer and explanation

Answer: B (7.5 × 1011 N m−2)

Explanation

E = (F/A) ÷ (e/L) = FL/(Ae) = (20 × 3)/(8 × 10−7 × 10−4) = 7.5 × 1011 N m−2.