Question

If 60% of the potential energy available in a waterfall is converted into heat energy, find the height of the waterfall, when the temperature difference between the top and the bottom of the fall is 0.21⁰C (sp. Heat cap. Of water = 4200J/kgK).

Answer 1

Given, Sp. heat capacity of water, s = 4200 J/KgK

Temperature difference, Δt = 0.21 °C

Let 'h' be the height of the waterfall and 'm' be the mass of water.

Then, P.E of the water = mgh

Given that, heat energy, H = 60% of P.E

or, 4200 x 0.21 = 0.6 x 10 x h 

or, h = `(4200 xx 0.21)/(0.6 xx 10) = 882/6` = 147 m