Consider two cylindrical rods of identical dimensions, one of rubber and the other of steel. Both the rods are fixed rigidly at one end of the roof. A mass $M$ is attached to each of the free ends at the center of the rods.

 The stress-strain graphs for two materials are shown in Figure (assume same scale).

 A wire is suspended from the ceiling and stretched under the action of a weight $F$ suspended from its other end. The force exerted by the ceiling on it is equal and opposite to the weight.

 A rod of length $l$ and negligible mass is suspended at its two ends by two wires of steel (wire $A$ ) and aluminium (wire $B$ ) of equal lengths (Figure). The cross-sectional areas of wires $A$ and $B$ are $1.0\mathit{ }m{m}^{\mathit{2}}$ and $2.0 mm{ }^2,$ respectively. $\left({\mathrm{Y}}_{\mathrm{Al}}=70\times {10}^9 \mathrm{N}·{\mathrm{m}}^{-2}\right.and \left.Y_{steel}=200\times {10}^9 {\mathrm{Nm}}^{-2}\right)$

For an ideal liquid

 A copper and a steel wire of the same diameter are connected end to end. A deforming force $F$ is applied to this composite wire which causes a total elongation of $1cm$. The two wires will have: