A 4.0-m-long steel wire has a cross-sectional area of 0.050cm^{2}. Its proportional limit has a value of 0.0016 times its Young's modulus. Its breaking stress has a value of 0.0065 times its Young's modulus. The wire is fastened at its upper end and hangs vertically.
a) How great a weight can be hung from the wire without exceeding the proportional limit? Take the Young's modulus for the rod to be Y=2.0 x 10^{11} Pa.
b) How much will the wire stretch under this load?
c) What is the maximum weight that the wire can support?