The force required to elastically stretch a wire is given by:(adsbygoogle = window.adsbygoogle || []).push({});

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?

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Force problem for elastic stretch

**Physics Forums | Science Articles, Homework Help, Discussion**