• question_answer Waterfalls from a height 500m. What is raise in temprature of water at the bottom. If the whole energy remain water. (Specific heat of water $4200\,J/k{{g}^{o}}C$). A)  ${{0.19}^{o}}C$              B)  ${{0.24}^{o}}C$C)  ${{0.40}^{o}}C$              D)  ${{1.16}^{o}}C$

Height of waterfall $h=500\,m$ Specific heat of water $s=4200\,J/k{{g}^{o}}C$ The potential energy of water             $=mgh$                 $=m\times 9.8\times 500$                 $=4900\,m$                     ??.(i) Increase in heat energy $=ms\,\theta =4200\,m\,\theta$       ?...(ii) (Where $\theta$ is the rise in temperature) As the entire potential energy of water is converted into heat energy. Hence, equating both the energies from (i) and (u), we get $4900\,m=4200\,m\theta .$ $\Rightarrow$               $\theta =\frac{4900}{4200}={{1.16}^{o}}C$