Find the diameter of an 18 m(L) long steel wire that will stretch no more than.009 m

Question

AL when a load stress of 3800 N is hung on the end of the wire. The Young's Modulus for steel wire is 200 x 109 N/m2?

Answer 1

delta L /L = tensile stress /E

.009 / 18 = 3800/ [ 2*10^11 (pi r^2) ]

solve for r then multiply by 2

Answer 2

3.48*10^-3 m