Question

A hydroelectric power station takes its water from a lake whose water level if 50 m above the turbine. Assuming an overall efficiency of 40%. calculate the mass of water which must flow through the utibinc each second to produce power output of 1 MV.

Answer 1

Potential enemy $mgh$
Efficiency $=40$%
Useful work done $=40$% of potential energy
$=\frac{40}{100}\left(mgh\right)=0.4\times (m\times 10\times 50)$
$=200m$
Power $=$ work done pr second
$1MW=200\times$ mass of water flowing each second
$1\times {10}^{6}w=200\times$ mass of water flowing each second
Mass of water flowing each second $=\frac{1\times {10}^6}{200}=5000kg$