Define the term stress.
Define the term strain.
Wires X and Y each have an unstretched length of $0.84\,\text{m}$ and are hung from fixed points at the same horizontal height. Their lower ends are fixed to a beam of negligible mass. The beam is horizontal and in equilibrium, as shown in Fig. 4.1. Wire X is made from a metal with a Young modulus of $1.9 \times 10^{9}\,\text{Pa}$. Wire Y is made from another metal. A load of weight $18\,\text{N}$ is hung from the beam at a point exactly midway between the two wires. This load causes both wires to extend by $0.47\,\text{mm}$.
Determine wire X's cross-sectional area.
Wire Y has a larger diameter than wire X. Explain, without calculation, whether the Young modulus of the metal used for wire Y is less than, the same as or greater than $1.9 \times 10^{9}\,\text{Pa}$.