16.01.2015
34 (10 )
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, : , , , .
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, m F ⃗ ( ) F ⃗ s ⃗ . A = F ∙ s. F = m∙a, s υ 1 υ 2 s = υ 22− υ 212 a.
A = F ⋅ s = m ⋅ a ⋅ υ 22− υ 212 a = m ⋅ υ 222− m ⋅ υ 212. (1)
, , .
E k.
Ek = m ⋅ υ 22. (2)
(1) :
A = Ek 2− Ek 1. (3)
, , .
(3), , , . . .
m υ, :
A = Ek 2− Ek 1= m ⋅ υ 22−0= m ⋅ υ 22. (4)
, υ, , , , .
.
. .
, .
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. , , .
, , . .
, F m h 1 h 2 (. 1). h 1 h 2 , F mg.
,
A = F ⋅ s = m ⋅ g ⋅(h 1− h 2). (5)
. 1
. (. 2) F = m∙g
A = m ⋅ g ⋅ s ⋅cos α = m ⋅ g ⋅ h, (6)
h , s , .
. 2
(. 3) h , h . . :
A = m ⋅ g ⋅ h ′+ m ⋅ g ⋅ h ′′++ m ⋅ g ⋅ hn = m ⋅ g ⋅(h ′+ h ′′++ hn)= m ⋅ g ⋅(h 1− h 2), (7)
h 1 h 2 , .
. 3
(7) , .
, . .
(7) :
A =−(m ⋅ g ⋅ h 2− m ⋅ g ⋅ h 1). (8)
, , , .
m , h 2, , h 1 , , .
A =−(Ep 2− Ep 1). (9)
p.
, , , . . , . , .
p , h , m g h :
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Ep = m ⋅ g ⋅ h. (10)
, , , .
, , , . m, h, h < h 0 (h 0 ), :
Ep =− m ⋅ g ⋅ h.
m , r ,
Ep = G ⋅ M ⋅ mr. (11)
G , ( p = 0) r = ∞.
m , h , M e , R e , h = 0.
Ee = G ⋅ Me ⋅ m ⋅ hRe ⋅(Re + h). (12)
m h (h R e)
Ep = m ⋅ g ⋅ h,
g = G ⋅ MeR 2 e .
, () x 1 x 2 (. 4, , ).
. 4
. (.. x) :
A = Fupr − cp ⋅(x 1− x 2), (13)
Fupr − cp = k ⋅ x 1− x 22.
A = k ⋅ x 1− x 22⋅(x 1− x 2)= k ⋅ x 21− x 222 A =−(k ⋅ x 222− k ⋅ x 212). (14)
, , :
Ep = k ⋅ x 22. (15)
(14) (15) , , :
A =−(Ep 2− Ep 1). (16)
x 2 = 0 x 1 = , , (14) (15),
Ep = A.