Define the Young modulus in terms of stress and strain.
A load of $F$ is hung from a fixed point by a steel wire. The way $F$ varies with extension $x$ for the wire is shown in Fig. 5.1.
State two quantities, other than the gradient of the graph in Fig. 5.1, that are needed to determine the Young modulus of steel.
Describe how the quantities you named in (i) may be measured.
A force of $3.0\ \text{N}$ is put on the wire. Use Fig. 5.1 to calculate the energy stored in the wire.
A copper wire has the same original dimensions as the steel wire. The Young modulus for steel is $2.2 \times 10^{11}\ \text{N m}^{-2}$ and for copper is $1.1 \times 10^{11}\ \text{N m}^{-2}$. On Fig. 5.1, sketch the change of $F$ with $x$ for the copper wire for extensions up to $0.25\ \text{mm}$. Do not stretch the copper wire beyond its limit of proportionality.