When the load applied to a wire is increased from 5 kg wt to 8 kg wt , the elongation of the wire increases…
When the load applied to a wire is increased from 5 kg wt to 8 kg wt , the elongation of the wire increases from 1 mm to 1.8 mm . The work done during the elongation of the wire is (Acceleration due to gravity $=10 \mathrm{~ms}^{-2}$ )
$47 \times 10^{-3} \mathrm{~J}$
$72 \times 10^{-3} \mathrm{~J}$
$25 \times 10^{-3} \mathrm{~J}$
$97 \times 10^{-3} \mathrm{~J}$
Solution
$\therefore$ The work done during elongation is
$\mathrm{w}=\Delta \mathrm{U}=\mathrm{U}_2-\mathrm{U}_1=\frac{1}{2} \mathrm{~F}_2 \mathrm{x}_2-\frac{1}{2} \mathrm{~F}_1 \mathrm{x}_1$
$=\frac{1}{2}(8 \times 1.8-5 \times 1) \times 10 \times 10^{-3}=47 \times 10^{-3} \mathrm{~J}$