Question

what is the force required for a steel wire to double its length when its area of cross section is 1 sqaure cm and young modulus is 200 Gpa, as the length of the wire is double, the change in length is equal to its original length

Answer 1

$$Y=\frac{Fl}{A\Delta l}\\Y=\frac{Fl}{Al}\\200\cdot10^9=\frac{F}{10^{-4}}\\F=2\cdot10^{7}\ N$$