The force required to elastically stretch a wire is given by: F= ( l - lo / lo ) EA where A is the cross-sectional area of the wire, lo is the length of the unstretched wire and l the length of the wire after it is stretched. E is the elastic modulus, sometimes called Young's modulus. Using this equation, compute the force as a function of distance stretched for the gold nanowire as it is stretched from E-I to E-II. The elastic modulus for bulk pure gold is 7.448 x 10^10 Pa. Is the behavior of the nanowire qualitatively/quantitatively different from that of the bulk? my work: l value = 10 Angstroms (from my graph of E-II) lo value = 8 Angstromgs (from my graph of E-I) F = (10-8)/8 * (7.448x10^10 Pa) A my problem is how would i find the value for the cross-sectional area of the wire (A)??? is there a formula i can use to calculate the cross-secitonal area?