What will be the temperature difference between the top and the bottom of a 400 m high waterfall, assuming that 80% of the heat produced is retained by the water?

Explanation

Work done, W = loss in potential energy
`= mg (h - 0) = mgh`
`:.` Heat produced , `H = W/J = (mgh)/(J)`
`:.` Amount of heat retained by water =`(mgh)/(J) xx 80/100`
If the increase in temperature of water is t, required heat = mst
According to the question,
`mst = (mgh)/J xx 80/100`
or, `t = (gh)/(Js) xx 80/100 = (9.8 xx 400)/(4.2 xx 1000) xx 80/100`
`[ :. "specific heat of water in SI",`
`s = 1000 cal cdot kg^(-1) cdot^(@)C^(-1)`]
or, `t = 0.747^(@)C`.