. . W , . Un.
.3.4.
, , .
. W Wn Wτ, . n - n +Un.
, W , α, n - n Un. Un , , (.3.5). ,
│ Un│=│W│cos α (3.2)
1890 . .. " ", " ". .
W'>W W' >W α'>α
.3.5.
, , , , . .
, :
1.
.
2.
.
, Wτ = 0, .
. , . , , , . , , .
|
|
- " ", .
.3.6.
.3.6.
, . .
.
Un . Un - . α ≤1, , . .
.
(.3.7).
.3.7. Un
:
Un = WCosα
dF = dSCosα
dV = WdF = UndS, Un/dF = W/dS Un = V/S,
V , S .
. , , Un, . , , " ", " " . , .