At $40\,^oC$, a brass wire of $1\, mm$ is hung from the ceiling. A small mass, $M$ is hung from the free end of the wire. When the wire is cooled down from $40\,^oC$ to $20\,^oC$ it regains its original length of $0.2\, m$. The value of $M$ is close to ........$kg$ (Coefficient of linear expansion and Young's modulus of brass are $10^{-5}/^oC$ and $10^{11}\, N/m^2$, respectively; $g = 10\, ms^{-2}$)

The loss in weight of a solid when immersed in a liquid at $0^o C$ is $W_0$ and at $t^o C$ is $W$. If cubical coefficient of expansion of the solid and the liquid by $\gamma_s$ and $\gamma_l$ respectively, then $W$ is equal to :

At $NTP$ water boils at $100°C.$ Deep down the mine, water will boil at a temperature

Why the density is changed of solid substances by increase in temperature ?

On what value of $\alpha _l$ depends ? Write its unit.

The diagram below shows the change in the length $X$ of a thin uniform wire caused by the application of stress $F$ at two different temperatures $T_1$ and $T_2$. The variation shown suggests that