(a(i))[1]
For the lines in Fig. 4.1, state what the gradient indicates.
(a(ii))[2]
For the lines in Fig. 4.1, explain why the area below the line represents the elastic potential energy of the wire.
(b)
Wires G and H are connected end-to-end so that they make a composite wire of negligible weight. The composite wire hangs vertically from a fixed support.
(b(i))[1]
Use Fig. 4.1 to find the extension x_G of wire G and the extension x_H of wire H.
(b(ii))[2]
Calculate the total elastic potential energy $E_P$ of the composite wire caused by the weight of the block.
(b(iii))[3]
The original length of wire G is $L$ and the original length of wire H is $1.5L$. Calculate the ratio $\dfrac{\text{cross-sectional area of wire G}}{\text{cross-sectional area of wire H}}$.