Power

1. The problem statement, all variables and given/known data



In a hydroelectric plant, water falls from a high elevation to a lower elevation,losing PE in the process/ In doing so, it turns turbines which generate electricity. In a particular hydroelectric plant, water flows at a rate of 400 kg/s. If 80% of the PE that the water loses gets converted to electricity, what is the power output of the dam, in watts?



2. Relevant equations



PE=mgy

PE lost=KE gained



3. The attempt at a solution



Known information:



m=400 kg/s (Right?)

g=9.8 m/s^2

y=30 meters



KE= .8(400 kg/s*9.8 m/s^2*30 m)=9408 Joules



That's easy enough, right? But don't a need a time to convert to Watts? Is the time just one second, so that my answer is 9408 Watts?



Thanks!