- .,. .. (.) , . . (.).
2 :, () F . F=ma=m(dv/dt),
m1 / m2 = a2/ a1 , P=mg, m1 / m2 = P2/ P1
F=d(mv)/dt=dp/dt . .
- , . - , .
- 3- . .
. , . . , . F 12 = - F 21
4 4 : (.. ),.(10-2 ,. . ),(10-5-10-10,-.-,..m↑ .),.
(10-40 ).
- . . - .
. . rc=mr1+mr2++mrn/m1+m2++mn
drc/dt=V0=(dm1r1/dt+dm2r2/dt++dmnrn/dt)*(1/ m1+ m2++mn)=
1/∑mi(m1V1+ m2V2++ mnVn)=P./=/
=MVc - .= .* .
.. , -.. . . . . . (). - -: . -.=0.
- . .
F=m dV/dt=dmV/dt=dp/dt; dmV=Fdt; ∫mV=∫Fdt; ΔmV=F Δt; p2-p1=∫FΔt
= .
. =0, .
, =0, =const.
=1+2++n=∑pi
- . , . .
- . . .
-. .. ,. .
A=Fs s=Fs cos a, dA=Fdr=Fcosa ds . F
A=∫ Fs s = ∫Fs cos a ()
- .
-, .
N=dA/dt=Fv ()
( ).
- , , , .
: F = -kr, r- - . A=kr12/2 kr22/2 - 1-2.
|
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. -F=-mgk; k- z . A=-∫mgdz = mg(z1-z2)
() F=a/r2; r - , a - . A=a/r1-a/r2.
- . .
, , . () - , . , . :, ∫Fdl=0; F=- ѵU; ѵxF=0.
- . .
-, , ,. .
A1-2 = Wp (1) - Wp (2)
dA=Fdr= - dWp, Wp = - ∫ Fdr+C
Fx = -∂Wp /∂x
... ∫Fdr =∫Fs cosadr =∫F τ dr =0
- .
W =mv 2 /2
(dA=Fdr, dA=dW, F=ma, A=Fs) δA=dmV2/2; A=∫dmV2/2= mV2/2│=E2-1
mV2/2 . .
...
.. . .
. ., . .
. .
- . .
.. - , . ., . ,.. .
W= W + Wp, dW/dt=0, W= W + Wp= const
. . . . .
. ., .
.
, .
- , .
- 2 , . . - 2 , ..,. , . .
m 1 V1 + m 2 V2 = m 1 v1 + m 2 v2
v1 = ((m 1 - m 2) V1 +2m 2V2 )/(m 1 +m 2)
v2 = ((m 2 - m 1) V2 +2m 1V1 )/(m 1 +m 2)
- .
.. ..
Vi=Vi+Vc; rc=m1r1+m2r2++mnrn/m1+m2++mn
K: =mVi2/2=(∑mi(Vc+ Vc)2)/2=+MVc2/2
miVi . - =0
miV/2 -..-.,. .
M=∑mi - -. .. .
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- , , .
. .. .
M=r x F=[r,F],
-,., . . .., =│r│*│F│sin r,F
.r F .( r . F, . )
, .
L=[r,p]= r x p
L r p . 2 .
- . , .
dL/dt=M .
.. 3 ..
dLz/dt=Mz; dLx/dt=Mx; dLy/dt=My.
- =0, . . .
dL/dt=∑Mi. - ..
.. = . .. . .
- . .
, , , . : (, ). J=∫r2dm [ 2]
.- : ε=M/I M=dL/dt -
,
,
- .
Ja , . J=∑miri2; Ja=∫r2dm=∫ρr2dV
- .
- , , m*(R*R), R - . J=Jc + md2
JC , ,
J ,
m , d .
- .
Wki=miVi2/2; Wk=ω2/2∑mir2i → Wk=J ω2/2; Wk= W+ W; Wk=mV2/2+ J ω2/2
- . . .
, , . , , .
, ,
PVm=RT; PV / T = const, m = const (P-Vm-.,R-. .,-.. )