A certain dam generates 120 MJ of mechanical (hydroelectric) energy each minute. If the conversion from mechanical to electrical energy is then 15% efficient, what is the dam's electrical power output in W?

electric energy (power) = 300000 W

Explanation:

given data

mechanical (hydroelectric) energy = 120 MJ/min = 2000000 J/s

efficiency = 15 % = 0.15

solution

we know that Efficiency of electric engine is expression as

Efficiency = Mechanical energy : electric energy ... 1

and here dam electrical power output is

put here value in equation 1

electric energy (power) = Efficiency * Mechanical energy (power)

electric energy (power) = 0.15 * 2000000 J/s

electric energy (power) = 300000 W