A liquid having coefficient of cubical expansion $\gamma $ is filled in the container having coefficient of linear expansion $\alpha $. If on heating the liquid overflows, then which of the following relations is correct?
$\gamma = 2\alpha $
$\gamma < 3\alpha $
$\gamma > 3\alpha $
$2\gamma = 3\alpha $
Explain why :
$(a)$ a body with large reflectivity is a poor emitter
$(b)$ a brass tumbler feels much colder than a wooden tray on a chilly day
$(c)$ an optical pyrometer (for measuring high temperatures) calibrated for an ideal black body radiation gives too low a value for the temperature of a red hot iron piece in the open, but gives a correct value for the temperature when the same piece is in the furnace
$(d)$ the earth without its atmosphere would be inhospitably cold
$(e)$ heating systems based on circulation of steam are more efficient in warming a building than those based on circulation of hot water
A metal rod of silver at $0°C$ is heated to $100°C$. It's length is increased by $0.19\, cm$. Coefficient of cubical expansion of the silver rod is
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
A beaker contains $200\,g$ of water. The heat capacity of the beaker is equal to that of $20\,g$ of water. The initial temperature of water in the beaker is $20\,^oC$. If $440\,g$ of hot water at $92\,^oC$ is poured in it, the final temperature (neglecting radiation loss) will be nearest to ........ $^oC$
Solids expand on heating because ................