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A wire of cross-section A is stretched horizontally between two clamps located 21 metre apart. A weight W kg is suspended from the mid point of the wire. If the mid point sags vertically through a distance x < l the strain produced is : |
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Answer» `(2x^(2))/(l^(2))` `DELTAL=[AC+BC]-2l` `=2(l^(2)+x^(2))^(1//2)-2l`  `=2l(1+(x^(2))/(l^(2)))^(1//2)-2l` `=2l[1+1/2(x^(2))/(l^(2))]-2l=(x^(2))/l` `therefore` STRAIN`=(Deltal)/(2l)=(x^(2))/(2l^(2))`. Correct choice is (c). |
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