, .
(, , ), , , , , , . , , , . , , , ; .
, , II. ( ) , , :
dA=-d. (12.2)
d F d r (12.2)
F d r =-d. (12.3)
, (r), (12.3) F .
(12.3)
, . . . , , , , . - ( ), .
F =-grad, (12.4)
(i, j, k ). , (12.5), .
grad Ñ. Ñ () , -:
. , , h ,
= mgh, (12.7)
h , 0 = 0. (12.7) , h .
, ( !}. , , , ( h'), =-mgh'.
|
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(). :
F = -kx,
Fx ; k ( ), , Fx , .
, , . .
Fx=-Fx =kx dA, Fx dx,
dA = Fx dx = kxdx,
. ,
=kx2/2.
, , . .
:
= +,
. . .
. . . (1711 1765), , . (18141878) . (1821 1894).
m1, m 2 ,..., mn, v 1, v 2,..., v n. F '1, F '2,..., F ' n , , a f 1, F 2,..., F n , . , , ; , , f 1, f 2,..., fn. v<<
:
, dt , d r 1, d r 2,..., d r n. , , dri = vidt, :
,
(13.1)
dT .
, , . . d (. (12.2)).
(13.1) ,
. ,
d(T+ )=dA. (13.2)
1 - 2
. . , . , (13.2) ,
d(+) = 0,
+ = E=const, (13.3)
. . . (13.3) : , , , . . .
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, ( ), . : .
, . . . , , .
, (-) . ( ) . , .
. , . , . , , , . , , .
, , , . , . . , , . .
.
( ) , . , , ( ), , . . , , , . .
. , . . , . , . e:
e = v'n/vn.
e=0, , e=1 .
0<e<1 (, e0,56, e0,89, e0). , .
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, , . , , . .
, , ,
.
.
m 1 m 2 v1 v2, v'1 v'2 (. 18). , . . : , .
(15.1) (15.2),
(15.3) (15.5),
.
(15.8) (15.9) :
) m 1 =m 2. (v 2=0)(. 19), (v'1=0), , (v' 2 = v 1 );
) m 1> m 2.
, , (v' 1 <v 1 ). , (v'2>v'1) (.20);
) m 1< m2. . , , , .. v' 2 <v 1(. 21);
) m 2>> m 1(, ). (15.8) (15.9) , v' 1 =-v 1, v' 2 2 m1v1/m2 0.
2) m 1= m 2 (15.6) (15.7)
v' 1 =v 2, v' 2 =v 1,
. . .
, , .
(), (. 22).
m1 m2, v1 v2, , ,
, , , . (m 1 =m 2 ),
v = (v1+v2)/2.
, . - , , , , , . , . :
(v 2 = 0),
m 2 >>m 1( ), v<<v 1 . , , . , (m 1 >>m 2 ), vv 1 , .
|
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, .
16.
. () , n :
. r , , z.
R (.23).
dr r r+dr. dJ = r2dm ( dr<<r, , r), dm ; 2prhdr. r , dm= r 2prhdr dJ = 2prr3dr.
p R'2h , m = pR2hr,
J = 1/2R2.
, , : J Jc , , m : J = Jc + ma2. (16.1)
1
(. 1) ( , ).
(. 1), z, (. 24). m 1, m 2 ,..., mn, r 1, r 2,..., rn . mi, ri vi. , :
w = v 1 /r 1 = v 2 /r 2 =... = vn/rn. (17.1)
:
(17.1),
Jz 2. ,
T = Jzw2/2. (17.2)
(17.2) (12.1) , (T= mv2/2), , . (17.2) , .
, , , :
m ; vc ; J , ; w .
.
F , - , , F (. 25):
M = [ rF ].
, F.
M = Frsina= Fl, (18.1)
a F; rsina = l .
z z, , 2 (.26). z z.
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z , -
, :
z = [ rF ]z.
(.27). F , r, a - r. , , . dj ds= rdj, :
dA=F sinardj. (18.2) (18.1), dA=Mzdj,
Fr sina = Fl =Mz z. , .
:
dA = dT,
, w=dj/dt,
(18.3) .
, (. 20), ,
J ( ).
, , . ? .
( ) , :
L = [ rp | = [ r m v ],
r -, A; p = m v (.28); L , r p.
L = rp sinalfa =mvr sinalfa= pl,
a r p, l .
z Lz, , . Lz z.