The increase in length is $l$ of a wire of length $L$ by the longitudinal stress. Then the stress is proportional to

Wires $W_{1}$ and $W_{2}$ are made of the same material having a breaking stress of $1.25 \times 10^{9} \, N/m^{2}$. $W_{1}$ and $W_{2}$ have cross-sectional areas of $8 \times 10^{-7} \, m^{2}$ and $4 \times 10^{-7} \, m^{2}$,respectively. Masses of $20 \, kg$ and $10 \, kg$ hang from them as shown in the figure. The maximum mass $m$ that can be placed in the pan without breaking the wires is $..... \, kg$. (Use $g = 10 \, m/s^{2}$)

The value of tension in a long thin metal wire has been changed from $T_{1}$ to $T_{2}$. The lengths of the metal wire at two different values of tension $T_{1}$ and $T_{2}$ are $l_{1}$ and $l_{2}$ respectively. The actual length of the metal wire is:

If the temperature increases,the modulus of elasticity

The substances having a very short plastic region are

Why is rubber used to make cycle seats instead of wood or iron?