Q 11-10-096JEE MainJEE Main 2021 (27 Aug, Shift 2)Easy
The height of victoria's falls is $63$ m. What is the difference in the temperature of water at the top and at the bottom of the fall? [Given $1$ cal $= 4.2$ J and specific heat of water $= 1$ cal g$^{-1}$ $^\circ$C$^{-1}$]
Answer: (C) $0.147^\circ$C
All the potential energy becomes heat in the water: $mgh = mc\,\Delta T$, with $c = 4200$ J kg$^{-1}$ $^\circ$C$^{-1}$.
$$\Delta T = \frac{gh}{c} = \frac{9.8\times63}{4200} = 0.147^\circ\text{C}$$
Solution by Sreeraj P, M.Sc Physics