The top of a waterfall is at a temperature `0.49^(@)C` below that of the bottom. The work done by water due to its fall is converted entirely into heat. Find the height of the waterfall. Given, `g = 980 cm cdot s^(-2), J = 4.2 J cdot cal^(-1)`.

Explanation

Let m = mass of water falling from height h.
Work done, W = kinetic energy of impact
= initial potential energy
=mgh.
Now, `W = JH or, mgh = J mst`
or, `h = (j st)/(g)`
`= (4.2 xx 10^(7))xx1xx(0.49)/(980)`
`= 21000 cm = 210 m`.