Two wires of the same material have lengths in the ratio $1 : 2$ and their radii are in the ratio $1 : \sqrt{2}$. If they are stretched by applying equal forces,the increase in their lengths will be in the ratio:

$A$ wire of length $2 \, m$ is made from copper having a volume of $10 \, cm^3$. When a force $F$ is applied,the extension in its length is $2 \, mm$. If a wire of length $8 \, m$ is made from the same volume of copper,what will be the extension in its length in $cm$ when the same force $F$ is applied?

$A$ metallic bar of Young's modulus $0.5 \times 10^{11} \,N \,m^{-2}$, coefficient of linear thermal expansion $10^{-5} \,^{\circ}C^{-1}$, length $1 \,m$, and area of cross-section $10^{-3} \,m^2$ is heated from $0^{\circ}C$ to $100^{\circ}C$ without expansion or bending. The compressive force developed in it is:

The Young's modulus for steel is much more than that for rubber. For the same longitudinal strain,which one will have greater tensile stress?

Two uniform rods $AB$ and $BC$ have Young's moduli $1.2 \times 10^{11} \, N/m^2$ and $1.5 \times 10^{11} \, N/m^2$ respectively. If the coefficient of linear expansion of $AB$ is $1.5 \times 10^{-5} /^{\circ}C$ and both have equal area of cross-section,then the coefficient of linear expansion of $BC$,for which there is no shift of the junction at all temperatures,is ............. $\times 10^{-5} /^{\circ}C$.

$A$ $5\, m$ long aluminium wire $(Y = 7 \times 10^{10}\, N/m^2)$ of diameter $3\, mm$ supports a $40\, kg$ mass. In order to have the same elongation in a copper wire $(Y = 12 \times 10^{10}\, N/m^2)$ of the same length under the same weight,the diameter should now be,in $mm$.