Part generator at Hoover Dam can supply 388 MW of electrical power. Assume that

ID: 2135768 • Letter: P

Question

Part

generator at Hoover Dam can supply

388 MW of electrical power. Assume that

the turbine and the generator are 83% effi-

cient.

Find the rate with which falling water must

supply energy to the turbine. The accelera-

tion due to gravity is 9.8 m/s2 .

Answer in units of MW

Part 2

The energy of the water comes from the

change of the potential energy (mg h). What

is the needed change in potential energy each

second?

Answer in units of J/s

Part 3

If the water falls 24.9 m, what is the mass of

the water that must pass through the turbine

each second to supply this power?

Answer in units of kg/s

1)effi=83%=0.83;power=388MW

RawPower *0.83 = 388
RawPower = 467.46MW

2) PE per second = Raw Power = 476.46 M W = 476.46 * 10^6 J/s

3) PE=m g h
m = PE / g h

h=24.9m;g=9.8m/s^2;PE=467.46* 10^6 J/s

m=467.46* 10^6/(9.8*24.9 )

m== 1.915 *10^6 kg/s