A hanging copper wire with diameter 1.4 mm ( m) is initially 3.5 m long. When a 36 kg mass is hung from it, the wire stretches an amount 1.83 mm, and when a 72 kg mass is hung from it, the wire...

A hanging copper wire with diameter 1.4 mm ( m) is initially 3.5 m long. When a 36 kg mass is hung from it,

the wire stretches an amount 1.83 mm, and when a 72 kg mass is hung from it, the wire stretches an amount 3.66 mm. A

mole of copper has a mass of 63 grams, and its density is . Find the approximate value of the effective spring

stiffness of the interatomic force.