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; $g = 10\, ms^{-2}$)

A steel tape $1 \;m$ long is correctly calibrated for a temperature of $27.0\,^{\circ} C .$ The length of a steel rod measured by this tape is found to be $63.0 \;cm$ on a hot day when the temperature is $45.0\,^{\circ} C .$ What is the actual length of the steel rod on that day ? What is the length of the same steel rod on a day when the temperature is $27.0\,^oC$? Coefficient of linear expansion of steel $=1.20 \times 10^{-5}\; K ^{-1}$

What is thermal expansion ? Write only its types.

A brass rod of length $50\; cm$ and diameter $3.0 \;mm$ is jotned to a steel rod of the same length and diameter. What is the change in length of the combined rod at $250\,^{\circ} C ,$ if the original lengths are at $40.0\,^{\circ} C ?$ Is there a 'thermal stress' developed at the junction? The ends of the rod are free to expand (Co-efficient of linear expansion of brass $=2.0 \times 10^{-5} \;K ^{-1},$ steel $=1.2 \times 10^{-5}\; K ^{-1} J$

A metallic tape gives correct value at $25^{\circ} C$. A piece of wood is being measured by this metallic tape at $10^{\circ} C$. The reading is $30 \,cm$ on the tape, the real length of wooden piece must be .......... $cm$

An ideal gas is expanding such that ${PT}^{3}=$ constant. The coefficient of volume expansion of the gas is: