Cooling rate of a sphere of $600\,K$ at external environment $(200\,K)$ is $R$ . When the temperature of sphere is reduced to $400\,K$ then cooling rate of the sphere becomes

A body cools from $60^{\circ} C$ to $40^{\circ} C$ in $6$ minutes. If, temperature of surroundings is $10^{\circ} C$. Then, after the next 6 minutes, its temperature will be $………{ }^{\circ} C$.

A body takes $10\, minutes$ to cool from $60\,^oC$ to $50\,^oC$. The temperature of surroundings is constant at $25\,^oC$. Then, the temperature of the body after next $10\, minutes$ will be approximately ……. $^oC$

Liquid is filled in a vessel which is kept in a room with temperature ${20^o}C$. When the temperature of the liquid is ${80^o}C$, then it loses heat at the rate of $60\;cal/\sec $. What will be the rate of loss of heat when the temperature of the liquid is ${40^o}C$ ……. $cal/\sec $

A container contains hot water at ${100^o}C$. If in time ${T_1}$ temperature falls to ${80^o}C$ and in time ${T_2}$ temperature falls to ${60^o}C$ from ${80^o}C$, then