A substance of mass $m\,kg$ requires a power input of $P$ $watt$ to remain in the molten state at its melting point. When the power is turned off, the substance completely solidifies in time $t\,sec$. The latent heat of fusion of the substance is
$\frac{{Pm}}{t}$
$\frac{{Pt}}{m}$
$\frac{{m}}{Pt}$
$\frac{{t}}{Pm}$
The rods of length $L_1$ and $L_2$ are made of materials whose coefficients of linear expansion are $\alpha _1$ and $\alpha _2$ respectively. If the difference between the two length is independent of temperatures, then
If the earth suddenly stops revolving and all its rotational $KE$ is used up in raising its temperature and if $'s'$ is taken to be the specific heat of the earth's material, the rise of temperature of the earth will be : ( $R -$ radius of the earth and $\omega =$ its angular velocity, $J =\,Joule$ constant)
$50\, gm$ of copper is heated to increase its temperature by $10\,^oC$. If the same quantity of heat is given to $10\, gm$ of water, the rise in its temperature is ........ $^oC$ (Specific heat of copper $=420\, Joule\, kg^{-1}\,^oC^{-1}$)
A cylindrical rod with one end in a steam chamber and the outer end in ice results in melting of $0.1 \,\,gm$ of ice per second. If the rod is replaced by another with half the length and double the radius of the first and if the thermal conductivity of material of second rod is $1/4$ that of first, the rate at which ice melts is $gm/sec$ will be
Two large holes are cut in a metal sheet. If this is heated, distances $AB$ and $BC$, (as shown)