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530(078)
22.377
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³ ̳ ( 5 24.12.09 .)
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. . ѳ, ,
. . , ,
. . , - ,
人, . .
18 . . 2 ( , ): / . . 人, . . , . . . ³: , 2010. 122 .
, , . .
. , , .
53(078)
22.377
. 人, . , . , 2010
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2
ͲͲ ˲
1. , :
= cos (w t + j0),
υ = - A w sin (wt + j0),
a = - A w2cos (wt + j0) = - w2 x,
;
w ;
j0 .
2. w n:
w = = 2 p n.
3. , 䳺 ( ):
F = ma = - m w2 x = - k x,
k = mw2 , , = 1.
4. ʳ, 㳿 :
,
,
.
5. :
)
+ x = 0, , T = 2p ;
)
+ x = 0, , = 2p ;
)
+ x = 0, , T = 2p ,
;
l ;
.
w w0.
6. , j0 :
,
tq j0 = ,
1 2 , ;
j1 j2 .
7. (w1 w2) , :
x = cos ,
.
, :
|
|
T = , T = .
8. :
cos(j2 - j1) = sin2 (j2 - j1),
1 2 , ;
j2 - j1 .
9. :
0
b = ;
r ;
.
10. :
x = A0e-bt cos (wt + a),
0-bt ;
w .
11.
δ= ln ,
δ ;
b ;
.
12.
w = w = .
13. :
T = = .
14.
q = 2p q = ,
Wt , t;
DW(t=T ) 㳿 ;
δ ;
b ;
w0 ;
( һ 0).
15.
,
F0 ;
w .
16. , 䳺 :
x = A cos (wt + a),
;
a .
17.
A = ,
f0 = ;
w0 ;
w .
18. :
tga = - .
19. :
w = ;
= .
1. = 0. w = 4 c-1. t = 0 0 = 25,0 , υ = 100 /. υ t = 2,40 .
:
w = 4 -1
0 = 25,0
υ= 100,0 /
t = 2,40
___________
? υ ?
. г :
x = A cos (w t + j). (1)
:
υ = - A w sin (w t + j). (2)
t = 0 υ 0 υ0:
x0 = A cos j i υ0 = - Aw sin j. (3)
(3), :
= 1 = ;
cos j = j = arc cos .
A = = 35,5 c,
j = arc cos .
, υ t:
x = 35,5 cos (4 × 2,40 + p/4) = - 20,2 ,
υ = - 35,5 × 4sin (4 × 2,40 + p/4) = 115,7 /.
³: = - 20,2 ; υ = 115,7 /.
2. x = A cos 2,1 t cos 50,0 t . , , .
:
x = A cos 2,1 t cos 50,0 t
|
|
_______________________
w1 ? w2 ? ?
. ³, w1 w2 :
= .
,
= 2,1 c-1 i = 50,0 c-1
w1 = 47,9 c-1; w2 = 52,1 c-1.
:
T = ,
.
T = = 1,49
³: w1 = 47,9 -1; w2 = 52,1 -1; = 1,49 .
3. = sin wt
y = cos wt, y. : ) () ; ) .
:
= sin wt
y = cos wt
___________
() ? ?
. г , (1) (2) :
sin wt = , cos wt = .
ϳ :
= sin2wt; = cos2 wt;
:
+ = 1 .
(.1):
1
, , :
) t = 0, = 0 = ;
) t = p/4, = = 0 ;
) t = T/2, = 0 = - . .
:
υ = wos wt; = - w2 sin wt = - w2 x;
υy = - w sin wt; ay= - w2 cos wt = - w2 y;
.
a = w2 = w2 r,
- .
- . ,
.
4. , , .2. ³ l = 20 , k = 0,18. , . .
: l = 20 k = 0,18 ________ ? | 2 |
. F1 i F2,
F1 = F2 =
r ;
S ;
k .
, , :
F = (F1 -F2) = - 2 r g S k x. (1)
:
F = m a. (2)
(1) (2),
ma + 2 r g S k x = 0
a
x = 0. (3)
(3) . :
w2 =
T = 2p
, m = rlS, :
T = 2p .
ϳ :
T = 6,28 = 1,5 .
³: = 1,5 .
5. Գ 120 o, , . ? ?
|
|
:
l = 120
_________
e ?
min ?
. ³ , Z (.3). , (j < 7), . - , . , .
M =- mga sin j, (1)
;
j .
sinj = j, Z,
Mz = - mga j, (2)
:
Mz = . (3)
(2) (3), :
I + mga j = 0.
:
j = 0. (4)
г (4) , :
(5)
;
.
:
I = I0 + m a2,
0 = ml2 , .
= m l2 + ma2. (6)
ϳ (6) (5)
T = 2p . (7)
, (7) :
= 0, .
2 a 2 - - a 2 = 0;
a e = . (8)
ae = 0,34 .
(8) (7) :
Tmin = 2p = 1,67 c.
³: = 34 ; min = 1,67 c.
6. m r R, . .
4
: , mg 1. 1 (.4.):
= - mgr sin a, (1)
mg ;
r ;
a - .
, a < 7, sin a = a.
M = - mgra. (2)
= b, (3)
, 1;
b 1.
(2) (3):
I b + mgr a = 0. (4)
:
I = mr2 + mr2 = mr2. (5)
b t r:
at = b r. (6)
t :
at = e (R - r), (7)
e , a (e = a);
(R - r) .
(6) (7) b:
b = . (8)
(5) b (8) (4), :
+ mgr a = 0.
= 0. (9)
(9) .
w = .
:
T = 2p .
7. ҳ 1 r = 0,05 /. k = 50 / , . ҳ , .5, . : ) b; ) n ; ) δ; ) N , ; ) .
m = 1
r = 0,05 /
k = 50 /
_____________
b ? n ? δ ?
|
|
N ? q ?
|
. (.5) F1 = F2 = kx, . :
Fn = - 2kx. (1)
, :
F0 = - r . (2)
. , :
(3)
г (3) :
= 0, (4)
= 2b, b ;
= w02, w0 .
(4) :
= 0. (5)
г (5) , :
x = A0 e-bt cos (wt + j). (6)
: )
b = = 0,025 c-1;
) n :
= 1,59 c-1;
)
δ = ln = 0,0157;
) , t, ,
N = ,
t , e pa;
.
t
1 = ln = b t,
t = .
N =
)
= 200.
³: n = 1,59 -1; δ= 0,0157; N = 64; q = 200.
8. 0 = 1 . , , , δ = 0,01?
:
0 = 1
δ = 0,01
_________
S ?
. , , , S1 = A0.
S2 =2A0 ; S3 = 2A0 ; S4 = 2 A0 × i ..
S = S1 + S2 + S3 +....+ Sn.
S = 0 + 20 + 20 + 20 +...+ 20 .
ϳ
S = A0 × .
,
Sn = ,
1 = ;
q = .
S = A0 × .
, b =δ,
S = 0,01 × = 4
³: S = 4 .
9. 10 / 10 . 0,1 /, : ) n0 ; ) n; ) , F0 = 0,02 ; ) i 䳺 F0.
:
k = 10 /
m = 10
r = 0,1 /
____________________
n0 ? n ? ? ?
. , , , 䳺 , . 䳿 :
m + r + kx = F0 cos w t. (1)
(1) m :
; ; ,
+ 2b × + w02 x = f cos wt. (2)
г (2) . o , :
x = A0e-bt cos(wt + j) + A cos (wt + j). (3)
䳺 . (2)
x = A cos (wt + j). (4)
(4) (2):
= - Aw sin (wt + j) = Awcos (wt + j + p/2),
= - Aw2 cos (wt + j) = Aw2 cos (wt + j + p),
Aw2 cos (wt + j + p) + 2 b Aw cos (wt + j + p/2) +
+ Aw2 cos (wt + j) = f0 cos wt. (5)
: 1 = Aw2; A2 = 2 b Aw; A3 = A w02; A4 = f0.
, 1, 2, 3, 4 (5) (.6)
A42 = A22 + (A3 - A1)2
, :
f02 = 4b2 A2 w2 + (w02 - w2) A2.
: 6
A = . (6)
(6) :
) w << w0, w 0
A = , (7)
䳺 F 0;
) w w0
A = , (8)
( b 0, p ¥).
(6):
= 0.
w = , (9)
w .
w (9) (6)
A = . (10)
b 0, A = , (8).
: ) n0
n0 = = 5,03 c-1;
) (9)
n =
= 4,91 c-1;
) (10)
A = = 6,4 × 10-3 ;
) , ,
= = 160.
³: n0 = 5,03 -1; n = 4,91 -1; = 6,4 ; q = 160.
ͲͲ ˲
1. г
,
Ux,t x ;
;
;
l ;
w .
г
,
r - .
3. :
υ ;
;
n .
4. ( ):
) :
;
r .
) :
,
G ;
r .
) :
,
K ᒺ ;
r .
) :
,
5. :
)
,
m = rSDx ;
;
)
)
) 㳿 㳿
6. 㳿
R = ,
㳿 .
7. 㳿
,
㳿 ;
.
8.
n,
;
n ;
;
υ ;
u ( ; ).
9. :
) ,
Dj = 2p 2n p,
2 - 1 ;
Dj ;
l ;
n = 0, 1, 2, 3,... max.
Dx = (x2 - x1) = n × l;
) , :
Dj = 2p .
D x = (x2 - x1) = (2n + 1) l/2.
10. г
ux,t =
ux,t ;
;
k = ;
w ;
.
)
kx = (2n + 1)p/2 x = (2n + 1)l/4,
n = 0, 1, 2, 3,...;
.
)
kx = np x = n l,
n = 0, 1, 2, 3,....