physics
posted by pat .
a metal wire 1.0 mm in diameter and 2.0 m long hangs vertically with a 5.0 kg mass suspended from it. if the wire stretches 1.2 mm under the tension, what is the value of the young's modulus for metal?

Stress = E*strain
E is Young's modulus
E*(delta L/L) = M*g/(pi*R^2)
deltaL/L  1.2/2000 = 6*10^4
is the strain
M*g/(pi*R^2) = 6.2*10^7 N/m^2
Solve for E. It is about 10^11 N/m^2