Question

5. A mass of 11.0 kg is suspended from a rigid support by an aluminium wire of length 2.0m, diameter 2.0mm and Young's modulus 7.0×10¹¹Nm⁻². Determine the extension produced. [g=10ms⁻², π=3.142]

Accepted Answer

Force = tension in wire = weight of the mass = 110N. Area = πd²/4 = 3.142×(2×10⁻³)²/4 = 3.14×10⁻⁶ m².
Extension produced = (Force × original length)/(Area × Young's modulus) = (110×2)/(3.14×10⁻⁶×7.0×10¹¹) = 1.00×10⁻⁴ m, or 0.10 mm.

WAEC Physics 2013 Theory — Question 5

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