Wire X is a thin metal wire with diameter $1.2 \times 10^{-3}\,\text{m}$, and it is used to support a model planet, as illustrated in Fig. 3.1. Fig. 3.2 shows how the stress for wire X changes with strain.
(a(i))[3]
The strain in X is $5.4 \times 10^{-3}$. Use Fig. 3.2 to calculate the force acting on the wire from the model planet.
(a(ii))[3]
Wire X has elastic potential energy of $0.31\,\text{J}$. Calculate the original length of the wire before the model planet was attached.
(b)[2]
Wire X is replaced with a new wire, Y, which has the same original length and diameter but twice the Young modulus of X. Wire Y also obeys Hooke’s law. On Fig. 3.2, draw a line showing the variation with strain of the stress for Y.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Stress value $\sigma=0.72\times10^9\,\mathrm{Pa}$” …