∫ ∫ ρφl dS = ρψ0 ∫ ∫ xl dS = ρψ0 (volume of the ellipsoid) = ψ0W′,
(23)
where W′ denotes the weight of liquid displaced.
Denoting the effective inertia of the liquid parallel to Ox by αW′. the momentum
αW′U = ψ0W′
(24)
| α = | ψ0 | = | A0 | ; |
| U | 1 − A0 |
(25)
in this way the air drag was calculated by Green for an ellipsoidal pendulum.
Similarly, the inertia parallel to Oy and Oz is