The flywheel effect, sometimes also referred to as "Mass Momentum", is a term used to describe the property of a system to remain at a given velocity or kinetic energy. It is generally applied to rotating mass, such as flywheels or clutch plates.
The following equations and calculator will estimate the Flywheel Effect or Polar Moment of Inertia.
Description 
Equation 
Flywheel Effect or Polar Moment of Inertia 

Mean Angular Velocity 

Coefficient of Steadiness 

Where:
Symbol 
Description 
Units 
Wk^{2} 
Flywheel Effect or Polar
Moment of Inertia 
kN (lbf) 
W 
Weight of Flywheel 
N (lbs) 
E 
Excess energy 
J (ftlbf) 
g 
Acceleration due to gravity 
9.8 m/s^{2}
(32.16 ft/s^{2)} 
n_{1} 
Maximum speed 
rpm 
n_{2} 
Minimum speed 
rpm 

Average speed 
rad/s 

Maximum and minimum
angular speed, respectively 
rad/s 
m 
Coefficient of Steadiness 
 
C_{f}

Coefficient of Fluctuation
of Rotation 
See Table 
Coefficient of Fluctuation of Rotation Table, Cf 
Driven machine 
Type of drive 
C_{f} 
AC generators, single or parallel 
Directcoupled 
0.01 
AC generators, single or parallel 
Belt 
0.0167 
DC generators, single or parallel 
Directcoupled 
0.0143 
DC generators, single or parallel 
Belt 
0.029 
Spinning machinery 
Belt 
0.02–0.015 
Compressor, pumps 
Gears 
0.02 
Paper, textiles, and flour mills 
Belt 
0.025–0.02 
Woodworking and metalworking machinery 
Belt 
0.0333 
Shears and pumps 
Flexible coupling 
0.05–0.04 
Concrete mixers, excavators, and compressors 
Belt 
0.143–0.1 
Crushers, hammers, and punch presses 
Belt 
0.2 
