Water falls from a height of $$60\,m$$  at the rate of $$15\,kg/s$$  to operate a turbine. The losses due to frictional force are $$10\% $$ of energy. How much power is generated by the turbine?
$$\left( {g = 10\,m/{s^2}} \right)$$

Solution :
Given, $$h = 60\,m,g = 10\,m{s^{ - 2}},$$
Rate of flow of water $$= 15\,kg/s$$
$$\therefore $$ Power of the falling water $$ = 15\,kg{s^{ - 1}} \times 10\,m{s^{ - 2}} \times 60\,m = 900\,watt.$$
Loss in energy due to friction $$ = 9000 \times \frac{{10}}{{100}} = 900\,watt.$$
$$\therefore $$ Power generated by the turbine $$ = \left( {9000 - 900} \right)watt$$
$$\eqalign{ & = 8100\,watt \cr & = 8.1\,kW \cr} $$