I am not sure that is a good analogy. In abstract terms you can think of the inertia as the time constant of a linear ODE. For the same perturbation of the sta

I am not sure that is a good analogy. In abstract terms you can think of the inertia as the time constant of a linear ODE. For the same perturbation of the state, the larger the inertia the slowest the variation. In a grid with low inertia changes in demand (wether increase or decrease demand) are very sudden and thus difficult to control.