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Question

Physics Question on mechanical properties of solids

A wire fixed at the upper end stretches by length by applying a force FF. The work done in stretching is

A

F2\frac {F}{2\ell}

B

FF\ell

C

2F2F\ell

D

F2\frac {F \ell} {2 }

Answer

F2\frac {F \ell} {2 }

Explanation

Solution

Let the area be A and length L of the string then the work done by the force is : W=12×stress×strain×volume=12×FA×1L×A×L=F12W =\frac{1}{2} \times { stress } \times { strain } \times { volume }=\frac{1}{2} \times \frac{ F }{ A } \times \frac{1}{ L } \times A \times L =\frac{ F 1}{2}