dl = gdΩ2p dp / 2ζW2cr.
From (1) and (3)
u = Wcτ / pΩ;
dl/u = gdΩ3p2 dp / 2ζW3c2τ2;
t = ∫p0p1 g dΩ3 p2 dp / 2ζW3c2τ2,
= g dΩ3 (p03 − p13) / 6ζW3c2τ2.
(14)
But
W = p0u0Ω / cτ;
∴ t = gdcτ (p03 − p13) / 6ζp03u03,
= ζ1/2 l3/2 (p03 − p13) / 6(gcτd)1/2 (p02 − p12)3/2;
(15)
If τ = 521°, corresponding to 60° F.,