Dann ist
(24) d p x d t = ∫ ϱ u x d S , d p y d t = ∫ ϱ u y d S , d p z d t = ∫ ϱ u z d S . {\displaystyle {\frac {d{\mathfrak {p}}_{x}}{dt}}=\int \varrho {\mathfrak {u}}_{x}dS,\quad {\frac {d{\mathfrak {p}}_{y}}{dt}}=\int \varrho {\mathfrak {u}}_{y}dS,\quad {\frac {d{\mathfrak {p}}_{z}}{dt}}=\int \varrho {\mathfrak {u}}_{z}dS.} {\displaystyle {\frac {d{\mathfrak {p}}_{x}}{dt}}=\int \varrho {\mathfrak {u}}_{x}dS,\quad {\frac {d{\mathfrak {p}}_{y}}{dt}}=\int \varrho {\mathfrak {u}}_{y}dS,\quad {\frac {d{\mathfrak {p}}_{z}}{dt}}=\int \varrho {\mathfrak {u}}_{z}dS.}