A wire $(Y = 2\ imes 10^{11}\ Nm^{- 2})$ has length 1 m and area of cross-section 1 $mm^{2}.$ The work required to increase its length by 2 mm is

Question

A wire $(Y = 2\ 	imes 10^{11}\ Nm^{- 2})$ has length 1 m and area of cross-section 1 $mm^{2}.$ The work required to increase its length by 2 mm is

Dr. Abubacker · Accepted Answer

(d) $Y = \frac{F}{A} 	imes \frac{l}{x}\ \ \ \ \ or\ F = \frac{YAx}{l}\ $
Work done $W = \frac{1}{2}\ F 	imes x = \frac{1}{2}\frac{YAx^{'}}{l}$
=$\frac{1 	imes 2 	imes 10^{11} 	imes \left( 10^{- 6} ight) 	imes \left( 2 	imes 10^{- 3} ight)^{2}}{2 	imes 1\ }$= 0.4 J

Q. A wire $(Y = 2\ \times 10^{11}\ Nm^{- 2})$ has length 1 m and area of cross-section 1 $mm^{2}.$ The work required to increase its length by 2 mm is

Explanation

Reviewed by Dr. Abubacker

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