The heat energy released by water of mass $2 \mathrm{~kg}$ when it is cooled by $10^{\circ} \mathrm{C}$ is…
The heat energy released by water of mass $2 \mathrm{~kg}$ when it is cooled by $10^{\circ} \mathrm{C}$ is
(Specific heat capacity of water $=4200 \mathrm{~J} \mathrm{~kg}^{-1} \mathrm{~K}^{-1}$ )
$42000 \mathrm{~J}$
$21000 \mathrm{~J}$
$63000 \mathrm{~J}$
$84000 \mathrm{~J}$
Solution
Mass, $\mathrm{m}=2 \mathrm{~kg}$
Temperature, $\Delta \mathrm{T}=10^{\circ} \mathrm{C}$
Heat capacity, $c=4200 \mathrm{JKg}^{-1} \mathrm{~K}^{-1}$
Heat energy is given by
$\begin{aligned} & \mathrm{Q}=\mathrm{mc} \Delta \mathrm{T}=2 \times 10 \times 4200 \\ & \mathrm{Q}=84000 \mathrm{~J}\end{aligned}$