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

delta L /L = tensile stress /E
.009 / 18 = 3800/ [ 2*10^11 (pi r^2) ]
solve for r then multiply by 2