If $60 \%$ of the kinetic energy of water falling from a $210 \ m$ high waterfall is converted into heat,the rise in temperature of the water at the bottom of the fall is nearly (specific heat of water $= 4.2 \times 10^3 \ J \ kg^{-1} \ K^{-1}$ and $g = 10 \ m/s^2$):

Two identical balls,$A$ and $B$,of uniform composition and initially at the same temperature,each absorb exactly the same amount of heat. $A$ is hanging from the ceiling while $B$ rests on the horizontal floor in the same room. Assuming no subsequent heat loss by the balls,which of the following statements is correct about their final temperatures,$T_A$ and $T_B$,once the balls have reached their final state?

Work done (heat energy required) in converting $1\,g$ of ice at $-10\,^{\circ}C$ into steam at $100\,^{\circ}C$ is ......... $J$. (Take specific heat of ice $= 0.5\,cal/g^{\circ}C$,latent heat of fusion $= 80\,cal/g$,specific heat of water $= 1\,cal/g^{\circ}C$,latent heat of vaporization $= 540\,cal/g$,and $1\,cal = 4.2\,J$)

Consider a rectangular sheet of solid material of length $l=9 \ cm$ and width $d=4 \ cm$. The coefficient of linear expansion is $\alpha=3.1 \times 10^{-5} \ K^{-1}$ at room temperature and one atmospheric pressure. The mass of the sheet is $m=0.1 \ kg$ and the specific heat capacity is $C_v=900 \ J \ kg^{-1} K^{-1}$. If the amount of heat supplied to the material is $8.1 \times 10^2 \ J$,then the change in area of the rectangular sheet is:

On which of the following four processes does the functioning of a bimetallic strip depend?
$(i)$ Radiation
$(ii)$ Energy conversion
$(iii)$ Melting
$(iv)$ Thermal expansion

The heat required to change $1 \,kg$ of ice at $-8^{\circ} C$ into water at $20^{\circ} C$ at $1 \,atm$ of pressure is closest to .............$\,kJ$. (Assume that ice has a specific heat capacity $2.1 \,kJ / kg \cdot K$,water has a specific heat capacity $4.2 \,kJ / kg \cdot K$,and the latent heat of fusion of ice is $333 \,kJ / kg$.)