1.1. A student investigates the mechanical properties of a copper wire. The wire has an original length of $2.50m$ and a cross-sectional area of $6.2\times{10}^{-8}{\text{m}}^{2}$. The student applies increasing loads and measures the extension of the wire.

Figure 5 shows the stress-strain graph obtained for the wire up to the point at which it fractures.

Figure 5

Determine the Young modulus of the copper wire using Figure 5.

1.2. Explain how the graph shows that copper wire is ductile.

1.3. Calculate the extension of the wire when a load of $25N$ is applied. Assume this load is within the proportional region.

1.4. A second wire, made of steel, has twice the diameter and half the length of the copper wire. The Young modulus of steel is $200\text{ GPa}$.

A student claims that the steel wire will extend less than the copper wire when the same load of $25N$ is applied.

Deduce whether this claim is correct. Support your answer with a calculation.