I was reading up on the mathematical modelling of Watt's governor from Brennan's Book on Differential Equations. The book has 2 equations one for the governor itself which I understand. However, there is an equation for the steam engine flywall & Drive shaft which I don't understand. This is the equation J * dΩ/dt = -β* Ω + τ This is the text following the equation J is the moment of Inertia of the flywheel Ω - rotational speed of the engine First term on the right is the torque due to the load & the second term on the right is the steam generated torque referred to the drive shaft. What exactly is β in the equation? What's the unit of β?