$A$ brass wire of length $2 \ m$ and radius $1 \ mm$ at $27 ^\circ C$ is held taut between two rigid supports. Initially, it was cooled to a temperature of $-43 ^\circ C$, creating a tension $T$ in the wire. The temperature to which the wire has to be cooled in order to increase the tension in it to $1.4 \ T$ is . . . . . . $^\circ C$.

$A$ metal string $A$ is suspended from a rigid support and its free end is attached to a block of mass $M$. $A$ second block having mass $2M$ is suspended at the bottom of the first block using a string $B$. The area of cross-sections of strings $A$ and $B$ are the same. The ratio of lengths of strings $A$ to $B$ is $2$ and the ratio of their Young's moduli $(Y_A/Y_B)$ is $0.5$. The ratio of elongations in $A$ to $B$ is . . . . . . .

$A$ metal rod of cross-sectional area $3 \times 10^{-6} \,m^{2}$ is suspended vertically from one end and has a length of $0.4 \,m$ at $100^{\circ} C$. The rod is cooled to $0^{\circ} C$, but prevented from contracting by attaching a mass '$m$' at the lower end. Find the value of '$m$'. (Given: $Y = 10^{11} \,N/m^{2}$, coefficient of linear expansion $\alpha = 10^{-5} /K$, $g = 10 \,m/s^{2}$) (in $\,kg$)

$A$ brass wire $1.8\; m$ long at $27\;^{\circ}C$ is held taut with little tension between two rigid supports. If the wire is cooled to a temperature of $-39\;^{\circ}C$,what is the tension developed in the wire,if its diameter is $2.0\; mm$? (Coefficient of linear expansion of brass $\alpha = 2.0 \times 10^{-5}\; K^{-1}$; Young's modulus of brass $Y = 0.91 \times 10^{11}\; Pa$)

If in case $A$,the elongation in a wire of length $L$ is $l$,then for the same wire,the elongation in case $B$ will be:

$A$ wire of cross-section $4 \; mm^2$ is stretched by $0.1 \; mm$ by a certain weight. How far (length) will a wire of the same material and length but of area $8 \; mm^2$ stretch under the action of the same force?