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8.Mechanical Properties of Solids
medium
The work done in increasing the length of a $1$ $metre$ long wire of cross-section area $1\, mm^2$ through $1\, mm$ will be ....... $J$ $(Y = 2\times10^{11}\, Nm^{-2})$
A
$0.1$
B
$5$
C
$10$
D
$250$
Solution
$\mathrm{W}=\frac{1}{2} \frac{\mathrm{YA}}{\ell}(\Delta \ell)^{2}$
$=\frac{1}{2} \times \frac{2 \times 10^{11} \times 1 \times 10^{-6}}{1} \times\left(10^{-3}\right)^{2}=0.1 \mathrm{J}$
Standard 11
Physics