Механика жидкости и газа_Свойства жидкостей и газов_Гидростатика_2022
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F F p S gh Hb g |
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F , F –
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( ,
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. 3.6, .
. 3.6.
D
-
F , -
F .
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arctg |
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. 3.6, |
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F , |
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( . 3.7), - |
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. 3.7. ( ) |
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, . 3.8. -
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ABC, -
ABC.
. 3.8. ABC
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p -
-
.
F = dlp, |
(3.18) |
d – ; l – . |
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pld = 2le , |
(3.19) |
– ; e – -
( ).
e = pd / (2 ). |
(3.20) |
, -
, -
e, (3÷7) . -
25%, .
, , -
, -
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F gW W , |
(3.21) |
W – ( -
). G -
3 :
1)F > G – ( );
2)F = G –
( );
3)F < G – .
( F = G ) :
gW gW W /W / , –
, W W – -
( ).
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3.2.
1. -
, 1,2 . -
( ).
.
(3.2)
pA p0 gh,
: p0 = pa = 1,0 = 9,81 104 ( -
), = 1000 3 ( -
), h = 1,2 ( ).
pA = 9,81 104 + 1000 9,81 1,2 = 109 872 = 1,12 .
2. -
h = 30,0 .
p , -
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.
.
, .
p gh 1000 9,81 30,0 = 294 300 .
3.
p0 -
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. 3.9) |
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h = 2,0 .
. -
, (3.2),
, , -
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. 3.9. 3
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. :
p0 pA gh 9,81 104 1000 9,81 2, 0 117 720
117, 72 0,12 .
. 3.10. 4
:
h h .
4. U -
( . 3.10).
N – N -
-
h = 8 .
h
.
. -
,
.
(3.2), -
pa gh pa gh .
h h h h h
h 1) 8 13600 /1000 – 1 100,8 .
5. -
= 3,5 ( . 3.11), -
( ) .
-
F R,
f = 0,35; G = 250 ;
h1 = 4,0 ; h2 = 1,2 .
. ,
,
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. ,
-
, ,
(F1) (F2):
F = F1 – F2.
. 3.11. 5
-
,
. -(3.7) -
:
F1 ghc1S1 g(h1 / 2)Bh1 gh12 B / 2
1000 9,81 3,5 42 / 2 274, 68 ;
F2 ghc 2S2 g(h2 / 2)Bh2 gh2 2 B / 2
1000 9,81 3,5 1, 22 / 2 24, 72 ;
F = 274,68 – 24,72 = 249,96 .
, ,
R = G + f·F = 250 9,81 + 0,35 249 960 = = 89 938,5 90 .
6. -
1 b
( . 3.12) R = 2,5 , = 60 .
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.
, -
F -
(3.14), , Fy = 0:
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F F 2 F 2 . |
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. 3.12. 2 |
(3.15) |
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H |
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F ghS |
z |
g |
Hb gH 2 |
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2 |
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H – .
OAC. OA = R/2 = 1,25 , .
ACO, 30 .
AC = H OAC
:
H 
R 2 OA2 
2, 52 1, 252 2,16 .
F = 1000 9,81 2,16 2 1,0/2 = 23,3 .
(3.11)
F gW gS ABC b,
SABC – ABC.
ABC -
BC. ABC ,
OBC
OAC.
SABC |
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d 2 |
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OA |
AC |
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4R2 |
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Rh |
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4 |
360 |
2 |
4 |
360 |
4 |
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3,14 2,52 60 / 360 2,5 2,16 / 4 1,89 .
F = 1000 9,81 1,89 1,0 = 18,9 .
B , 2
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-
F 
23, 32 18, 92 29, 7 .
, F -
, . .
F (3.17)
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F |
18,9 |
39,19 . |
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arctg |
B |
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arctg |
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F |
23,3 |
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7. G = 1230 ,
G = 735 . -
.
. ,
, F
F = G – G = 1230 – 735 = 495 .
(3.21)
F gW W ,
– ; W – , -
G
, . W = G / .
= G / F = 1000 9,81 1230 / 495 = 24376,36 3.
4.
1. ,
V1 = 0,025 3 1 =
920 3 V2 = 0,035 3 2 = 870
3.
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2. ( -) : ( = 790 3) – 30%, -
( = 850 3) – 70%.
3.
L = 1500 d = 120 -
p1 = 1,5 p2 = 2,5 . -
V, . -
P = 4,75·10–10 1/ .
4.
d = 0,5 L = 25
p1 = 5,8 . p2 = 4,0 .
, ,
. -
P = 4,75·10–10 1/ .
5. -
, V = 100 3,
t1 = 11 °C t2 = 90 °C.
t = 0,00072 1/° .
6. d = 400 L = 1500 p1 = 400 , -
t1 = 7 °C. ,
, -
t2 = 12 °C,
P = 5,18·10–10 1/ ,
t = 150·10–6 1/° .
7. ,
5%. -
P = 4,75·10–10 1/ .
8. (
) L = 700 ,
d = 0,2 p1 = 0 p2 = 2,0 . ,
,
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. -
= 2000 .
9. 70 3
0,08 3 . -
, -
= 2·109 .
10. ,
R = 287 /( )) -
t = 250 .
, = 0,8 .
11.
-
b h = 3 ,
d = 0,4 , , -
, = 5 .
. 4.1. 11 = 950 3.
12.
0 ,
, ,
h = 0,3 . -
= 0,12 , = 13600 3.
13.
. 4.2. |
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12, 13 |
- |
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h = 0,7 , |
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= 1000 3, = 0,12 .
14. h ,
,
= 0,7·105 . = 13600 3.
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