a 2.0 m long copper wire of circular cross section and diameter 1.0 mm hangs by one end from a fixed support. when a 5.0 kg mass is hung from the wire's bottom end, the wire stretches by 1.1 mm. by treating the interatomic bonds as ideal springs and using the ideas of series and parallel effective spring constants, we can use this information to estimate the spring constant of a single bond in copper.