A  wire fixed at the upper end stretches by length $l$ by applying a force $F$ The work done in stretching is Option 1) $F/2l$ Option 2) $Fl$ Option 3) $2Fl$ Option 4) $Fl/2$

P perimeter

As we learnt in

Work Done in Stretching Wire / Elastic P.E. -

$=\frac{1}{2}\frac{YAl^{2}}{L}=\frac{1}{2}Fl$

- wherein

L - Length of wire

$l$ - increase in length

Work done by constant force

$W=\frac{1}{2}\times stress\times strain \times volume$

$W=\frac{1}{2}\times \frac{F}{A}\times \frac{l}{L}.AL=\frac{Fl}{2}$

$W=\frac{Fl}{2}$

Correct option is 4.

Option 1)

$F/2l$

This is an incorrect option.

Option 2)

$Fl$

This is an incorrect option.

Option 3)

$2Fl$

This is an incorrect option.

Option 4)

$Fl/2$

This is the correct option.

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