Friction

The input energy is given by the potential energy of the falling water, which is:

E_%7B%5Ctext%7Binput%7D%7D%20%3D%20mgh

Where: -

m%20%3D%2020%20%5C%2C%20%5Ctext%7Bkg%2Fs%7D

is the rate of flow of water, -

g%20%3D%209.8%20%5C%2C%20%5Ctext%7Bm%2Fs%7D%5E2

is the acceleration due to gravity, -

h%20%3D%2080%20%5C%2C%20%5Ctext%7Bm%7D

is the height of fall. Substitute the values:

E_%7B%5Ctext%7Binput%7D%7D%20%3D%2020%20%5Ctimes%209.8%20%5Ctimes%2080%20%3D%2015680%20%5C%2C%20%5Ctext%7BJ%2Fs%7D%20%3D%2015.68%20%5C%2C%20%5Ctext%7BkW%7D

Now, 20% of the input energy is lost, so the energy available to the turbine is:

E_%7B%5Ctext%7Boutput%7D%7D%20%3D%20(1%20-%200.20)%20%5Ctimes%20E_%7B%5Ctext%7Binput%7D%7D%20%3D%200.80%20%5Ctimes%2015.68%20%3D%2012.8%20%5C%2C%20%5Ctext%7BkW%7D

Thus, the power generated by the turbine is

12.8%20%5C%2C%20%5Ctext%7BkW%7D

Chapter Questions
1 MCQs