Question

A dam is situated at a height of 550 metres above sea level and supplies water to a power house which is at a height of 50 metres above sea level. 2000 kg of water passes through the turbines per second. The maximum electrical power output of the power house if the whole system were $80\%$ efficient is

• A. 8 MW
• B. 10 MW
• C. 12.5 MW
• D. 16 MW

Answer 1

The correct option is A

8 MW

$Power=\frac{workdone}{time}=\frac{mg\Delta h}{t}=\frac{2000\times 10\times (550-50)}{1}=10MW$

But the system is $80\%$ efficient

$\therefore$ Power output $=10\times 80\%=8MW$