A body cools from a temperature 3T to 2T in 10 minutes. The room temperature is $T$. Assume that Newton’s law of cooling is applicable. The temperature of the body at the end of next 10 minutes will be

In the Ingen Hauz’s experiment the wax melts up to lengths 10 and 25cm on two identical rods of different materials. The ratio of thermal conductivities of the two material is

A small metal sphere, initially at $100^\circ C$, is placed in air at $20^\circ C$. The sphere cools to $80^\circ C$ in 5 minutes. Which of the following statements is true about the time it takes for the sphere to cool from $80^\circ C$ to $60^\circ C$, assuming Newton's law of cooling?

Two rods A and B are of equal lengths. Their ends are kept between the same temperature and their area of cross-sections are ${A_1}$ and ${A_2}$ and thermal conductivities ${K_1}$ and ${K_2}$. The rate of heat transmission in the two rods will be equal, if

There is formation of layer of snow $x\,\,cm$ thick on water, when the temperature of air is $- {0^0}C$ (less than freezing point). The thickness of layer increases from $x$ to $y$ in the time $t$, then the value of $t$ is given by

If the initial temperatures of metallic sphere and disc, of the same mass, radius and nature are equal, then the ratio of their rate of cooling in same environment will be

In determining the temperature of a distant star, one makes use of

A hot body at $80^\circ C$ cools to $64^\circ C$ in 5 minutes and to $52^\circ C$ in 10 minutes. The temperature of the surroundings is:

Two rectangular blocks $A$ and $B$ of different metals have same length and same area of cross-section. They are kept in such a way that their cross-sectional area touch each other. The temperature at one end of $A$ is $\,{100^{\rm{o}}}C$ and that of $B$ at the other end is ${0^{\rm{o}}}C$. If the ratio of their thermal conductivity is 1 : 3, then under steady state, the temperature of the junction in contact will be

Four rods of identical cross-sectional area and made from the same metal form the sides of square. The temperature of two diagonally opposite points are $T$ and $\sqrt 2 T$ respectively in the steady state. Assuming that only heat conduction takes place, what will be the temperature difference between other two points

Newton's Law of Cooling is most accurate when the temperature difference between the body and the surroundings is: