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TRANSFERUL DE IMPULS - Cadre Didactice

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Forte de suprafata<br />

•Forţa unitară de suprafaţă (tensiunea,<br />

efortul unitar) se defineşte prin relaţia:<br />

r<br />

F<br />

s = ΔA<br />

lim<br />

0<br />

r<br />

ΔFs<br />

ΔA<br />

=<br />

r<br />

dF<br />

s<br />

dA<br />

Δ = forţa de suprafaţă aplicată<br />

s<br />

ΔA = aria care mărgineşte<br />

volumul de fluid ΔV<br />

• Formula dimensională:<br />

r Forta Masa ⋅ Acceleratie<br />

−1 −<br />

Fs = =<br />

= M ⋅ L ⋅T<br />

Suprafata Suprafata<br />

• Dpdv matematic, forţele superficiale<br />

sunt mărimi tensoriale de ordin 2.<br />

F r<br />

FENOMENE <strong>DE</strong> TRANSFER SI OPERATII UNITARE 44<br />

2

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