, . .. .
, .
, , , ( ) ( ) (, ). . , , , .
, , , . , , .
, , , . , , , . , , . f = 1/ , . , = 1, (): 1 = 1-1
, , . : , , .. . ; , , , . . , , .
( 2π), ,
x(t) = A cos(ω0t + α), x(t) = A sin(ω0t + α1), (1)
, ω0, α, α1 .
, ( ), , - . , , .
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ω0 . 2π, ( ) ω0
T = 2π/ω0. (2)
, t (t + T)
(t) = (t + T). (3)
(3) (1) ,
ω0 = 2π/T = 2π ν. (4)
ω0 () . - (/c), ν , ().
. , (. 1)
(1)
φ (t) = ω0t + α (5)
. (5) , t = 0
α = φ, (6)
α .
(1) ( (t)). , . (1),
vx = dx/dt = -A ω0 sin (ω0t + α) = A ω0 cos(ω0t + α + π/2). (7)
, , 1/2 π. , 1/2 π. , x , , . ( )
vmax = A ω0. (8)
, Fx = , . . (7) ,
ax = = - A ω2 0 cos(ω0t + α), (9)
(1)
ax = - ω0 2x = A ω2 0 cos(ω0t + α + π). (10)
(1), , . 1.
1
1. x(t) = A sin (ω t + φ) 1. 2. v = x'(t) = ω A cos(ω t + φ) 2. 3. a = v'(t) = - ω2 A sin (ω t +φ) | 1. x(t) =A cos(ω t + φ) 2. v = x'(t) = - ω A sin(ω t + φ) 3. a = v'(t) = - ω2 A cos(ωt + φ) |
φ = 0 | |
4. x(t) = A sin ∙ ω t 5. v = ω A cos ω t = ω A sin (ω t + ) = ω A(sin ω t · cos + cos ω t · sin ) = ω A cos ω t 6. a = - ω2 A sin ω t = ω2 A sin(ω t + π) | 4. x(t) = A cos ω t 5. v = - ω A sin ω t = ω A· cos(ω t + ) = ω A(cos ω t · cos -sin ω t · sin ) = - ω A× ×sin ω t 6. a = - ω2 A cos ω t = ω2 A × cos (ω t + π) |
7. tg φ = ; A2 = | 7. tg φ = - ; A2 = |
8. A cos ω t + B sin ω t = cos(ω t δ) | |
cos δ = | sin δ = |
9. A cos ω t + B sin ω t = sin(ω t + δ) | |
sin δ = | cos δ = |
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(10) , , , π. ( )
amax = A ω02. (11)
m
m = = ,
(10)
ma = Fx, Fx = -m ω0 2x. (12)
, , , . ( ).
(12) . - ( x = 0), = = 0, , . Fx (x) : x = 0 Fx = 0, (. 2).
x . , , . Fx x = 0 , Fx x, . , .
Fx = - kx (13)
( k , , () ), (13) (12) ,
k = m ω20 (14)
ω0 = , (15)
T = = 2π . (16)
, (
.1. . , -
.2.
U(0) = 0 x
.3. ,
), . , , . . , α , , .. x0 = (t = 0) υ0= υ(t = 0). (1) (7),
(17)
(17) α,
A = , α = - arctg . (18)
, α ( , ) (17)
- (, 0 v0) , , .
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(13), . , U (x) x = 0 ( (. 3)). F (x) x
Ux = A (F) (19)
F (x) x,
A = <F> (x 0) = x = . (20)
,
U = , (21)
, (15)
U = . (22)
T = (23)
(2) (3) (23) (24),
U = cos2 (ω0 t + α) = (1 + cos 2(ω0 t + α)) (24)
T = sin2 (ω0 t + α) = (1 - cos 2(ω0 t + α)) (25)
.. , , , , . .
E = T + U = = const (26)
Tmax = (27)
, ,
Umax = (28)
, . ( ) 0,5E:
< T > = < U > = 0,5E. (29)
- m, l . , ( , , mg, )
= 0 (30)
.. m .
m l
α = l θ, (31)
θ ( ) (.4). , , , , , (.. , , ). . 4 ,
Fx = - mg sin θ (32)
, (31),
Fx = - mg sin (x/l) (33)
(33) , Fx x . , . , , x << l, x/l << 1 sin (x/l) tg (x/l) x/l.
Fx = - mg (34)
x,
k = . (35)
,
x(t) = A cos(ω0t + α)
ω0 = = (36)
T = = 2π . (37)
, T0 = 1 ( g0 = 9,81 /2) 24,8 .
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h h ( ), . g h, ,
T = 2π (38)
( T0 R3 ), h
T = 2π > 0 . (39)
, , h << R3, (38) 1/ (1 + h/2R3).
T T0 (40)
, , , ,
.4.
.4.
(, , - ).
,
= 0 (41)
(41), , , (), () .
(41)
(42)
(43)
.. , . , (42) (30) , (30) , (42) - . , , (30) , , , . , , ,
ω0 = (44)
T = 2π , (45)
g = (46)
- () .
, . , . , ( ) , , , , . , , , ,
= (47)
(44) (45),
g = .
1. α (.5). l, .
g¢ (. 5). , , :
(g¢')2 = 2 + g2 + 2g sin α. (48)
ω2 = g1 /l.
. 5. ( 1)
m, , . .
m , , , , , , (, ).
= ,
.. ( )
Δl = . (49)
, x, , , kx. , ( )
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Fx = - kx
, x,
k = ,
,
ω0 = (50)
T = 2π
, , (49).
, ( ) , , , , . , ( , ) , .
, , . . L S. ( ) F. σ = . ε = . ε = . . F = kx, k = . .
2.1.4.
- , , . , . , . 6, , , . .
2. q m, l h -
.6.
( ), . . . .
.7. , .
AB = BC = h; AD = Δh; l = ç ç- ; - -, .
, () (. 7).
Fk.
+q . q. . , , . , ( ) .
, . , B, . , 2h. Fk = . , , α.
α Δh = l(1 cos α). Fk:
Fk = .
, ,
<< 1 .. << 1
.
( ) J0 = ml2, l . ,
N = (mg + Fk)lsinα. (51)
PD = l sinα - .
, :
= [ , ]
, = J0 . ( )
J0α" = - (mg + Fk) lsinα, (52)
α" = ε = .
(52) sin α ≈α
α" + l α = 0
ω02 = , ω0 . , ω012 = mg/J0. , ω022 = Fk/J0. ω02 = ω012 + ω022. n ,
ω02 = . (53)
, .