Answer:
[tex]2.65\cdot 10^9 W[/tex]
Explanation:
The power produced by the water falling down the Falls is
[tex]P=\frac{E}{t}=\frac{mgh}{t}[/tex]
where
E = mgh is the potential energy of the water, with m being the mass, g the gravitational acceleration, h the height
t is the time
In this problem we have
[tex]\frac{m}{t}=6.0\cdot 10^6 kg/s[/tex] us the mass flow rate
h = 50 m is the height
g = 9.8 m/s^2 is the acceleration of gravity
Substituting,
[tex]P=(6.0\cdot 10^6 kg/s)(9.8 m/s^2)(50 m)=2.94\cdot 10^9 W[/tex]
And since the efficiency is only 90%, the power output is
[tex]P_{out} = (0.90) (2.94\cdot 10^9 W)=2.65\cdot 10^9 W[/tex]
