ICSE Class 10 Answered

Efficiency = 40% 

Work done = 40% × Potential energy 

 

P.E = mgh 

 

m = ? 

g ≈10 m/s² 

h = 50 m 

 

Thus,

 

useful work done = 40 % × (m × 10× 50)

= (40/100) × (500 × m)

= 200 m 

 

We know, 

Power = Work done/ time 

t = 1 s 

1 MW = 200 × mass of water flowing per second 

 

1 MW = 1 × 10⁶ W

 

Thus,

1 × 10⁶ W = 200 × m 

 

m = 10⁶ / 200

m = 5000 kg 

 

Thus, 5000 kg mass of water must flow through turbine per second to produce a power output of 1MW.