ME2040 - 010100 Cac Khai Niem Co Ban Va Tien de Tinh Hoc

7/25/2019 ME2040 - 010100 Cac Khai Niem Co Ban Va Tien de Tinh Hoc

1/19

C HC K THUT

TNH HC VT RN

CHNG

Cc khi nim c bnv h tin tnh hc


2/19

Chng 1. Cc khi nim c bn v h tin tnh hc

Ni dung

1 - 2

1. M u v tnh hc vt rn

2. Cc khi nim c bn v mt s nh ngha

3. H tin tnh hc4. Lin kt v phn lc lin kt


3/19


1. M u v tnh hc vt rn

1 - 3

Tnh hc vt rn (Tnh hc)l phn th nht cagio trnh Chc k thut, cp ti hc thuyt v lcv scnbng ca vtrn ditc dng cacc lc.

Ni dung ca phn Tnh hc bao gm:

- Xy dng cc khi nim c bn- L thuyt v thu gn h lc- Tm iu kin cn bng ca mt vt rn v h nhiu vt rn- Xc nh phn lc lin kt, ni lc cc mt ct ca vt rn.

Phng php nghin cu Tnh hc: phng php tin vphngphp m hnh.


4/19



1 - 4

Ba khi nim c bn ca Tnh hc lLc, Vt rn tuyt iv Cn bng

F

Lc l i lng o tc dng c hc gia cc vt th vi nhau

- Lc c xc nh bi ba yu t: ln, hng tc dngv im t, c biu din bng i lng vct, th d

- n v ca lc l Newton, k hiu l (N).

2

m1N 1kg 1

s

Phng tc dng lc

Hng tc dng lc

im t lc


5/19



1 - 5

Biu din vct lc trong h to Descartes vung gc

yh FF sin

yy FF cos cossin cos

sin

sin sin

x h

y

z h

y

F FF

F F

F

3D2D

sinyF F

cosxF F


6/19



1 - 6

Vt rn tuyt il tp hpcc cht immkhongcch giahai im bt k can lun

lun khng i.- Khi ccbin dng ca vt rn nh,ta c

th bqua v xem l vt rn tuyt i.

- Quy c gi tt vt rn tuyt il vt rn.

CnbngMt vt rn c gil cnbng nun ngyn (khng thay i vtr) so vi mt

hquy chiu chn.- Hquy chiu: Vt c chn lm mc

theo di chuyn ng ca vt th.- Vt ngyn so vi hquy chiu c nh:

Cnbng tnh.


7/19



1 - 7

1F

2F

nF

kF

H lc: Tp hp cc lc tc dng ln mt vt rn

1 2, ,..., ,..., .k nF F F F Hai h lc tng ng nu c cng tc dng

c hc nh nhau i vi vt rn

1 2 1 2, ,..., , , ..., .n mF F F G G G

Hp lc ca h lc l mt lc tng ng vih lc

1 2, ,..., .nR F F F H lc cn bng khng lm thay i trng thi

c hc (ng yn, chuyn ng) ca vt rn

1 2, ,..., 0.nF F F

Ngu lc l mt h gm hai lc song song,ngc chiuv c cng ln

1 2, .F F

1 2F F

1F

2F


8/19



1 - 8

Cnbng ca h nhiu vt rn: Mt h nhiuvt rn c gil cn bng nu mi vt rn

thuc hcnbng.

Vt rn t do l vt rn c th thc hin mi dichuyn b t v tr ang xt sang v tr ln cnca n mt cch ty .

Vt rn chu lin kt c t nht mt di chuynno b cn tr.


9/19


3. H tin tnh hc

1 - 9

Tin 2 (Tin v thm vo hoc bt i mt cp lc cn bng)Tc dng ca mt h lcln vt rn tdo khng thay i nuta

thm vo hoc bt i mt cp lccnbng. ngha: Quy nh mtphpbin i tng ng c bn v lc.

Tin 1 (Tin v s cn bng ca vt rn)

iu kin cnv cho mt vt rn tdo cnbng di tc dng ca hai lcl hai lcny cchung mt ngtc dng,cng lnv ngcchiunhau.

ngha: Quy nh mttiu chuncnbng ca vtrn tdo ditc dng ca h lc n gin nht.


10/19


3. H tin tnh hc

1 - 10

Tin 3 (Tin hnh bnh hnh lc)

Hai lc tvo cng mt imth c hp lc t tiim ng quy v c xc nh bng ngcho ca hnh bnh hnh m hai cnh l hai lcthnhphn cho.

ngha: Quy nh mtphpbin i tng ng

c bn v lc.

Tin 4 (Tin tc dng v phn tc dng)Lctc dng tng h giahai vt thl hailc c chung mt ng tc dng, cng ln, nhng ngc chiunhau.

ngha: L c s kho st bi ton hnhiu vt rn.


11/19


3. H tin tnh hc

1 - 11

Tin 5 (Tin ha rn)

Mt vt bin dngtdo trngthi cn bng ditc dng ca mt h lcnu rn li, n vn trngthi cnbng ditc dng ca h lc .

ngha: Qui nh iu kin cn vt th bin dng cn bng (h lctcdngln nphi thamn cc iu kincnbng ca vt rn tuyt i).

Nguyn tc trt lc

H qu t h tin tnh hc

Nguyn tc ba lc cn bngng phng v ng qui


12/19


4. Lin kt v phn lc lin kt

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Lin kt l nhng iu kin cn trdi chuyn ca vt kho st.

Lc xut hin ch tip xc hocni ghp gia cc vt rn c gil lc lin kt.

Lclin ktdo vtgy lin kttcdngln vt khost c gil

phn lcl in kt.

Vt gy lin kt

Vt chu lin kt(vt kho st)


13/19



1 - 13

i tng ca cctin tnh hc

Nguyn l gii phng lin kt Lagrange (Tin 6 ca tnh hc).

Mt vt rn chu lin kt cn bngc thxem l mt vt rn tdo cn bngnuta giiphng cc lin kt,thay tc dng cacclin kt c giiphngbngccphn lclin kt tng ng.

i tng thc


14/19



1 - 14

t s

m hnh ph

ng c

a lin k

t

Lin kt ta (phn lc lin kt c chiu xc nh)

Vt kho st

Lin kt dy (phn lc lin kt c chiu xc nh)


15/19



1 - 15

t sm hnh phng ca lin kt

Lin kt thanh (phn lc lin kt c chiu cha xc nh)

Lin kt bn l (phn lc lin kt c phng v chiu cha xc nh)


16/19



1 - 16

t sm hnh phng ca lin kt

Lin kt ngm

Lin kt rnh trt (mng trt)


17/19



1 - 17

Th d v gii phng lin kt

Vt rn chu lin kt cn bng Vt rn t do cn bng(h 3 lc cn bng ng qui)

h kh i i b h i h h


18/19



1 - 18

Th d v gii phng lin kt

Vt rn chu lin kt cn bng Vt rn t do cn bng(lin kt ta v bn l )

AY

AX

BN

Ch 1 C khi i b h i h h


19/19


Chng tip theo

1 19

Chng 1. Cc khi nim c bn v h tin tnhhc

Chng 2. H lc phng v cn bng ca vt rn

phng

Chng 3. H lc khng gian v cn bng ca vtrnkhng gian

Chng 4. Trng tm vt rn

Chng 5. Ma st gia cc vt rn
http://localhost/var/www/apps/conversion/tmp/scratch_2/chuong%2002.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_2/chuong%2002.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_2/chuong%2002.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_2/chuong%2002.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_2/chuong%2002.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_2/chuong%2002.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_2/chuong%2002.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_2/chuong%2002.ppt

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ME2040 - 010100 Cac Khai Niem Co Ban Va Tien de Tinh Hoc