# Homework Help: Dam turbine power problem

1. Jan 23, 2006

### aud11888

a mill requires 5000kW to operate at full capacity, produces 14tons of paper per hour, purchases electricty for \$.10/kW*hr

There is a dam 10m high that supplies water to a turbine. the river can be used only if the flow is above 50 cubic ft/sec. efficiency of generator is 75%

how am i supposed to find "What percentage of the mill's power requirement can the dam supply?" i'm so lost

2. Jan 23, 2006

### durt

Each second, 50 ft^3 of water transfers its kinetic energy to the mill. This energy will be equal the water's potential energy at the top of dam. So $$E = m g h$$, where m is the mass of the water (mass = density * volume), and h is the height of the damn (let's assume the water comes out at the bottom). So the power is .75 * E per second. Divide this into how much power the mill needs to get the percentage.