It takes $10$ minutes to cool a liquid from $61^{\circ} C$ to $59^{\circ} C$. If the room temperature is $30^{\circ} C$,then the time taken in cooling from $51^{\circ} C$ to $49^{\circ} C$ is .......... $min$.

$A$ body cools from $80^{\circ} C$ to $50^{\circ} C$ in $5 \text{ min}$. In the next time of $t \text{ min}$, the body continues to cool from $50^{\circ} C$ to $30^{\circ} C$. The total time taken by the body to cool from $80^{\circ} C$ to $30^{\circ} C$ is
[The temperature of the surroundings is $20^{\circ} C$.] (in $\text{ min}$)

If a body cools from a temperature of $62^{\circ} C$ to $50^{\circ} C$ in $10 \, \text{minutes}$ and to $42^{\circ} C$ in the next $10 \, \text{minutes}$, then the temperature of the surroundings is (in $^{\circ} C$)

$A$ body cools from $50.0^{\circ}C$ to $49.9^{\circ}C$ in $5\;s$. How long will it take to cool from $40.0^{\circ}C$ to $39.9^{\circ}C$? Assume the temperature of surroundings to be $30.0^{\circ}C$ and Newton's law of cooling to be valid. The time taken is ....... $s$.

The temperature of an iron block falls from $100 \, ^\circ\text{C}$ to $90 \, ^\circ\text{C}$ in time $t_1$,from $90 \, ^\circ\text{C}$ to $80 \, ^\circ\text{C}$ in time $t_2$,and from $80 \, ^\circ\text{C}$ to $70 \, ^\circ\text{C}$ in time $t_3$. Then:

$A$ solid cube and a solid sphere of identical material and equal masses are heated to the same temperature and left to cool in the same surroundings. Then,