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 :

Three rods of equal length $l$ are joined to form an equilateral triangle $PQR.$ $O$ is the mid point of $PQ.$ Distance $OR$ remains same for small change in temperature. Coefficient of linear expansion for $PR$ and $RQ$ is same i.e. ${\alpha _2}$ but that for $PQ$ is ${\alpha _1}$. Then relation between ${\alpha _1}$ and ${\alpha _2}$ is

Two straight metallic strips each of thickness $t$ and length $\ell$ are rivetted together. Their coefficients of linear expansions are $\alpha_1$ and $\alpha_2$. If they are heated through temperature $\Delta T$, the bimetallic strip will bend to form an arc of radius

Calculate the stress developed inside a tooth cavity filled with copper when hot tea at temperature of $57\,^oC$ is drunk. You can take body (tooth) temperature to be $37\,^oC$ and $\alpha = 1.7 \times  10^{-5}/^oC$, bulk modulus for copper $ = 140 \times 10^9\, N/m^2 $.

The weight of sphere in air is $50\ g$. Its weight $40\  g$ in a liquid, at temperature $20\,^o C$. When  temperature increases to $70\,^o C$ , it weight becomes $45\  g$, then the ratio of densities of liquid at given two temperature is