Water flows over a section of Niagara Falls at a rate of 1.2×106 kg/ s and falls 50m. How many 60W bulbs can be lit with this power?

Answer 1

And what efficiency do you assume for 1)the turbine, and 2) the electrical generator?

Let efficiency be E.

Power output= massflowrate*g*50m*E

Now, divide that by 60 to find the number of 60w bulbs.