# A steel wire having a radius of 2.0 mm, carrying a load of 4 kg, is hanging from a ceiling. Given that $g=3.1\; \pi ms^{-2},$ what will be the tensile stress that would be developed in the wire ? Option 1) $4.8\times10^{6}Nm^{-2}$ Option 2) $5.2\times10^{6}Nm^{-2}$   Option 3) $3.1\times10^{6}Nm^{-2}$   Option 4) $6.2\times10^{6}Nm^{-2}$

Answers (1)

$r=2mm$

$m=4kg, g=3.1\pi \; ms^{-2}$

So, $F = mg$

Stress = $\frac{F}{A}=\frac{mg}{\pi r^{2}}=\frac{m\pi \times3.1}{\pi (4)\times10^{-6}}$

Stress = $\frac{4\times3.1\times\pi }{\pi \times10^{-6}\times4}=3.1\times10^{6}N/m^{2}$

Option 1)

$4.8\times10^{6}Nm^{-2}$

Option 2)

$5.2\times10^{6}Nm^{-2}$

Option 3)

$3.1\times10^{6}Nm^{-2}$

Option 4)

$6.2\times10^{6}Nm^{-2}$

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