A cuboid $ABCDEFGH$ is anisotropic with $\alpha_x = 1 × 10^{-5} /^o C$, $\alpha_y = 2 × 10^{-5} /^o C$, $\alpha_z = 3 × 10^{-5} /^o C$. Coefficient of superficial expansion of faces can be

A hole is drilled in a copper sheet. The diameter of hole is $4.24 \,cm$ at $27.0^{\circ} C$. Diameter of the hole when it is heated to $35^{\circ} C$ is ...........

A metal ball immersed in alcohol weighs ${W_1}$ at $0°C$ and ${W_2}$ at $59°C.$ The coefficient of cubical expansion of the metal is less than that of alcohol. Assuming that the density of metal is large compared to that of alcohol, it can be shown that

The coefficient of linear expansion depends on

A seconds pendulum clock has a steel wire. The clock shows correct time at $25^{\circ} C$. .......... $s$ time does the clock lose or gain, in one week, when the temperature is increased to $35^{\circ} C$ ? $\left(\alpha_{\text {toel }}=1.2 \times 10^{-5} /{ }^{\circ} C \right)$

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