Density of water at 4^° C and 20^° C are 1000 kg / m^3 and 998 kg / m^3 respectively. The increase in internal energy of 4 kg of water when it is…

Density of water at $\displaystyle 4{ }^{\circ} \mathrm{C}$ and $\displaystyle 20^{\circ} \mathrm{C}$ are $\displaystyle 1000 \mathrm{~kg} / \mathrm{m}^3$ and $\displaystyle 998 \mathrm{~kg} / \mathrm{m}^3$ respectively. The increase in internal energy of $\displaystyle 4$ kg of water when it is heated from $\displaystyle 4$ °C to $\displaystyle 20^{\circ} \mathrm{C}$ is $\displaystyle \_\_\_\_$J. (specific heat capacity of water $\displaystyle =4.2 \mathrm{~J} / \mathrm{kg}$. and $\displaystyle 1$ atmospheric pressure $\displaystyle =10^5 \mathrm{~Pa}$ )