Question

A wire of a length 1m and diameter of 0.4mm is hung from a ceiling. Find the extension caused in the wire, by attaching a weight of 100N, if the material of the wire has the Young's modulus E = 200$\times {10}^{11}$Nm

• A. 1 mm
• B. 0.1 mm
• C. 0.2 mm
• D. 2 mm

Answer 1

The correct option is A 1 mm

(a) $\frac{stress}{E}=strain$
Stress = force\area $=\frac{100}{crossectionalarea}$ = $\frac{100}{\left(\frac{p}{4}\right)}(8\times {10}^{-}4)2$ Pa = Q.$1)99\times {10}^8$Pa
Strain = $99\times \frac{108}{200}\times 1011=0.995\times {10}^{-3}$ m= 0.995mm~1mm