In a flywheel, the maximum and minimum speeds in a cycle are 180 and 120 rpm, respectively. Then, the coefficient of fluctuation of the speed is

Concept:

Coefficient of fluctuation of speed:

The ratio of the maximum fluctuation of speed (N1 - N2) to the mean speed (N) is called the coefficient of fluctuation of speed. 

\({C_s} = \;\frac{{{N_1} - {N_2}}}{N} = \;\frac{{2\left( {{N_1} - {N_2}} \right)}}{{{N_1} + \;{N_2}}}\)

Calculation:

Given:

N1 = 120 rpm, N2 = 180 rpm

Coefficient of fluctuation of speed:

\({C_s} = \;\frac{{{N_1} - {N_2}}}{N} = \;\frac{{2\left( {{N_1} - {N_2}} \right)}}{{{N_1} + \;{N_2}}}\)

\({C_s} =\frac{{2\left( {{180} \;- \;{120}} \right)}}{{{180} \;+ \;{120}}}=\frac{2\;\times\;60}{300}=0.4\)