Question

A steel wire has the following properties: Length = 5.00 m Cross-sectional area = 4.60×10−2 cm2 Young's modulus = 2.0×1011Pa Shear modulus = 0.84×1011Pa Proportional limit = 3.60×108Pa Breaking stress = 11.0×108Pa The proportional limit is the maximum stress for which the wire still obeys Hooke's law (point B in (Figure 1)). 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?

B) How much does the wire stretch under this load?

C) What is the maximum weight that can be supported?

Answer 1

Given data:

Length of steel wire = 5 m

Cross-sectional area =

Propotional limit =

Breaking stress =

Concept:   stress = load/cross-sectional area

(a)