Question

The force required to stretch a steel wire of $1$ sq. cm cross-section to $1.1$ times, its length would be $(Y=2\times {10}^{11}N{m}^{-2}$)

• A. $2\times {10}^{6}N$
• B. $2\times {10}^{8}N$
• C. $2\times {10}^{-6}N$
• D. $2\times {10}^{7}N$

Answer 1

The correct option is D $2\times {10}^{7}N$

Young's modulus $Y=\left(F/A\right)/\left(\Delta L/L\right)$

As the length of the wire is doubled, the change in length is equal to its original length.

If Lis the original length, then $\Delta L=L$.

Therefore$Y=F/A$

$F=YxA=2x1011\left(N/m2\right)x(10-2m)2$ .

$=2x{10}^{7}N$