A hanging wire made of an alloy of aluminum with diameter 0.12 cm is initially 2.8 m long. When a 40 kg mass is hung from it, the wire stretches an amount 1.57 cm. A mole of aluminum has a mass of 27 grams, and its density is 2.7 g/cm3.
Based on these experimental measurements, what is Young's modulus for this alloy of aluminum?
Y = N/m2
As you've done before, from the mass of one mole and the density you can find the length of the interatomic bond (diameter of one atom). This is 2.55 10-10 m for aluminum. As shown in the textbook, the micro quantity ks,i (the stiffness of one interatomic bond) can be related to the macro property Y:
ks,i = N/m