Question

A hydroelectric power station uses the gravitational potential energy of water to generate
electrical energy.
In one particular power station, the mass of water flowing per unit time is 1.5 x 10kgs. The
water falls through a height of 120m.
The electrical power generated is 100 MW.
What is the efficiency of the power station?
A
5.6%
B
43%
C
57%
D
68%

Answer 1

Answer:

let the efficiency be x%

power generated=100Mw= 10^5 w

power genrate by falling water= mgh

= 1.5×10^3× 10 × 120

= 18×10^5

it is given that

10^5=x%of 18 × 10^5

1=x/100 × 18

x=100/18

x= 5.55

thus we can say option A will be correct

hope this will help you

Answer 2

Answer:

C

Explanation:

GPE=M*H*G then 100mw=100*10^6 so efficiency=EP/GPE *100