P
k e lib c h iq a d i. B u n i (7 .3 ) ga q o ‘ y ib q u y id a g i fo rm u la g a ega boM am iz:
— (
'y-dA = M
P
a
In te g ra l o s tid a g i ifo d a Z o ‘ qiga nisbatan k e s im n in g in e rs iy a m o m e n ti
e k a n lig in i eslasak, o x irg i fo rm u la q u y id a g i k o ‘ rin is h n i o la d i.
1
M
Т
ы
™
(7 .5 )
n i (7 .4 ) ga q o ‘ y ib , izlanayotgan fo rm u la g a , y a ’ n i s o f e g ilis h h o
la ti boMgan b a lk a n in g k o 'n d a la n g k e sim id a y o tg a n istalgan n u q ta n in g n o r
m al k u c h la n is h in i a n iq la sh fo rm u la sig a ega boM am iz:
M у
=
(7-6)
E n d i Z o ‘ q in in g h o la tin i o y d in la s h tira m iz . B u n in g u ch u n (7 .6 ) fo rm u la -
da a n iq la n g a n k u c h la n is h cr n in g q iy m a tin i (7 .3 ) da k e ltirilg a n ik k ita teng
lam a q o ‘ y a m iz :
— [
vdA
= 0;
—
f y z dA =
0
Jz л
Jz A
B u ye rd a
boM gani uchun
JydA =
0 va
jyzd A =
0 boMadi.
J Z
A
A
In te g ra lla rn in g b ir in c h is i k e s im n in g s ta tik m o m e n tin i, ik k in c h is i esa
m a rkazdan q o c h irm a in e rs iy a m o m e n tin i ifo d a la y d i. B ir in c h i in te g ra l Z o ‘ qi
k e s im n in g o g M rlik m a rka zid a n o ‘ tis h in i, y a ’ n i n e y tra l o ‘ q e k a n lig in i angla-
ta d i. Ik k in c h i in t e g r a t in g nolg a teng boM ishi у v a z o ‘ q la ri k e s im n in g bosh
m a rk a z iy o ‘ q la ri e k a n lig id a n d alolat beradi.
O lin g a n n a tija la rn i ta h lil q ila m iz.
(7 .5 ) fo rm u la yo rd a m c h i ta riq a s id a c h iq a rilg a n b o ‘ lsada, a s lid a m usta-
q il a h a m iy a tg a egadir. B u fo rm u la d a g i 1/r ba lka e g ilg a n o 'q in in g e g rilig i
deb a ta la d i. D em ak, b a lk a n in g e g rilig i e g u v c h i m o m e n tg a to ‘ g ‘ ri, E I2 ga
teskari p ro p o rs io n a l ekan. B u ye rd a EJ2 b a lk a k e s im in in g e g ilis h d a g i b ik r li
gi deb a ta la d i va N m : b ila n oM chanadi. F o rm u la n in g o ‘ z in i esa e g ilish d a g i
G u k q o n u n i deb atasa ham boM adi, c h u n k i fo rm u la d e fo rm a ts iy a (1 /r) b ila n
kesim ga ta ’ s ir etayotgan m om ent o ra sid a g i b o g ‘ la n is h n i ifo d a etadi.
( 7 .6 ) fo r m u la g a k o ‘ ra n o rm a l k u c h la n is h la r k e s im n in g s h a k li va
o ‘ lc h a m la rid a n q a t’ iy nazar, n e ytra l c h iz iq d a n o l boM adi. N e y tra l c h iziq d a n
uzoqlashgan sari no rm a l k u c h la n is h n in g q iy m a ti o rtib b o rib ,
n e ytra l c h i
z iq d a n e n g uzoq nuqtada m a ksim u m g a e ris h a d i (7 .1 6 -ra s m ).
N e y tra l ch iz iq d a n yu q o rid a g i to la la r s iq ila d i, pa std a g ila ri c h o ‘ z ila d i. Egu
v c h i m o m e n tn in g y o ‘ nalishi o'zgarsa, y u q o rid a g i to la la r c h o 'z ila d i, pastda
g ila ri esa s iq ila d i. A g a r rasmdagi k u c h la n is h la r
epyurasiga e’ tib o r berilsa,
balka k o ‘ nda lan g ke sim in in g eng k o ‘ p ishla yd ig a n q is m i u n in g ch e tki qism -
Iari, y a ’ ni n e ytra l o ‘ qdan eng uzoqda yotgan q a tla m la ri e k a n lig i k o ‘ zga tash-
lanadi. K e s im n in g o ‘ rta q ism id a g i m a te ria l d e y a rli ish la m a yd i. M a te ria ln in g
« is h la m a y d ig a n » q is m in i « c h iq a rib ta sh la sh » g 'o y a s i ana shundan k e lib
c h iq q a n . N a tija d a q o ‘ shtavr, ta v r va s h v e lle r ka b i s h a k lli p r o filla r paydo
boMgan. B a lk a n in g ko 'n d a la n g ke sim i ana shunday s h a klla rd a boMsa, b ir to
m ondan m a te ria l tejaladi, ik k in c h i to m o n d a n ko n stru ksiya yeng illa sh a d i.
B a lk a n in g m u s ta h k a m lig in i n o rm a l k u c h la n is h o rq a li te k s h iris h d a , (7 .6 )
fo rm u la d a g i e g u v c h i m om ent M n in g o ‘ rn ig a
m a k s im a l e g u v c h i m om ent
M m ax, у n in g o 'rn ig a у m ax q o ‘ y ila d i, shunda b a lk a n in g x a v fli k e s im id a
g i eng k a tta n o rm a l k u ch la n ish k e lib c h iq a d i:
neytral chiziq
7.
16-rasm.
2
F o rm u la n i boshqacha k o ‘ rin is h d a y o z a m iz :
in a x
j
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