, i- , , :
dA = Fcosαdl
, dt , dl, , : dl = Rdφ.
, dA = Fcosαdl = FcosαRdφ
, : M = RF.
, :
dA = Mcosαdφ = (M dφ)
:
A = ∫dA = ∫ Mcosαdφ = ∫(M dφ)
III. .
(Wk) (Wp). , , .
.
, F, m V1 V2.
dA = Fdr
(4)
. , . , .
, , : . , .
, V1 V2: = D
, A < 0 .
, . .
, :
Vi = ωri; J = mR2
:
, :
, .
(11)
: ,
(12)
W W.
, .
- , .
|
|
( ) , , .
. 1.9
d r F dA = F d r. ( V = 0 V = 0), , ( ) , , .. .
dWp . , :
(5)
, F, , .
(5) :
) dA > 0, (dWp < 0).
) dA < 0, (dWp > 0).
, , :
(6)
.
S.
- , , . , , .
(6) :
) .
) , , , .
(5) , . Wp ( ). , , ( ).
:
1. .
dWp = -Fdr
:
, r1 = 0, ( ), r2 = H, ( )
Wp = mgH
2. .
dA = Fdx = kxdx
. 1.10 |
, . , .
, :
W = Wk +Wp
, .