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NGHIEN CU\J a U>IG DUNG HINHTHANH DINH LUATPAXCANTlTTHi NGHIEM TUTAO TRONG DAY HOC VAT U CJTRUdNG P H 6 THONG''''i 1 Dinh lugt Paxcan Id mgt ttong nhftng djnh lu$t co bdn ciia ca hgc chdt luu trong chuon[.]
NGHIEN CU\J a U>IG DUNG HINHTHANH DINH LUATPAXCANTlTTHi NGHIEM TUTAO TRONG DAY HOC VAT U CJTRUdNG P H THONG'i Th.S Mai Ng9c Anh Tnrdng DH Hong Due Thanh Hda Dinh lugt Paxcan Id mgt ttong nhftng djnh lu$t co bdn ciia ca hgc chdt luu chuong trinh vgt If phd thdng Su dyng djnh lugt Paxcan giiip ta gidi thich dugc m^t cdeh tign vpn qud trinh truyen dp suat Idng chat luu va cdc nguyen tdc hoat dgng cua mdy ^p diing chat long la logi mdy hoat dgng dya tren co sd ciia dinh lugt Cd the ndi dinh ludt Id CO sd nen tdng giiip cho HS hgc tiep nhftng ndi dung, nhung phan tiep theo ciia co hpc chat luu Vi vgy, ngudi ta coi dinh luat Paxcan nhu sgi chi dd xuyen sudt phan ca hgc chat luu chuong trinh vdt If danjg gidng day d cac trudng phd thdng hien Tam quan ttgng ciia dinh lugt la vay, nhien qua tim hieu thuc te gidng dgy phan ndy, ehiing tdi thay phan ldn GV van chii yeu hinh thdnh dinh lugt bang dudng If thuyet dung cu thi nghipm van cdn thieu Thanh thu, giang day, GV van gap rdt nhieu khd khan qua trinh hinh kien thuc, cdn HS thi tiep thy bdi mdt cdeh miln cudng va thy ddng De HS tiep thu bdi mpt each thuan lgi, hieu qua vd phdt huy dugc tinh tieh eye, ty lyc, sdng tgo cua minh ttong hgc tap thi cdn phdi ty tgo nhiing dung cy thi nghiem thay thl, day la mdt viec Idm rdt cd y nghia frong day hgc doi vdi mSi GV Cd nhieu cdeh chl tgo bp thf nghipm diing dl hinh thdnh djnh luat Paxcan tu nhilu cdc vgt lipu r^ tien de kiem khdc nhau, bai viet ndy gidi thipu cdeh che tgo bg thf nghipm tten nhdm phyc vy eho qud trinh dgy - hgc ciia GV vd HS d cdc trudng trung hgc thdng T M T A T LI THUYfiT CO BAN 2.1 Ap suat thuy tlnh Bat ki mpt vat ndo ndm khdi chat Idng (hodc chat khi) ciing bi chat Idng (ho§c chat khi) nen lgi O trgng thdi tTnh, dp luc mdt chat Idng (hay khi) tdc dyng len mgt dipn tich nhd A^ tten bl m§t cua vat cd phuong vudng gdc vdi A5, cd chieu hudng tu chat long ve AS" va cd dg ldn khong phu thugc vdo nghieng cua AS ma chi phy thugc vdo vi tri cao thdp ciia AS chdt long [1.3,5,6.7] Gid su AF la dp lyc tac dyng len dipn tfeh dii nhd AS nam ttong ehdt Idng thi lyc gay tten be mdt vgt mgt dp sudt p=^ Ap sudt dugc gay bdi dp lyc tren dugc ggi Id dp sudt thuy tTnh (ggi tdt la dp suat) Ngudi ta da chiing minh dugc dp sudt thiiy tTnh tai mgt dilm Idng chdt Idng dugc xdc dinh bdi cdng thuc[1,3,5,6,7]: P^Dgh+Pf^ (1) Trong dd: A'gay nhgn bai 25/9/2012; Ngay duy?i dang 25/12/2012 • TAP CHITHIETBI GIAO DUC-50 89-01/2013 P^ Ld dp suat khf quyln D: Kh6i lugng rieng cua chat Idng g: Gia toe trgng trudng 2.2 Djnh lu^t cff bdn ciia thuy tlnh h^c ^^ yM^y-:yf^-y Hinh I Xet hai diem A, B ridm mpt chat Idng can bdng dyng mpt binh cd djnh, cd dg sdu lan lugt Id hAvd h^ (hinh 1), tir cong thuc (1) ta tinh duac dp sudt tgi hai diem: P,=Dgh,+P, (2) Ps=Dghs+Po (3) TCr (2) va (3) suy ra: PB-PA=Dg(hB-hA) (4) Bieu thirc (4) dien td dinh lugt CO ban ciia thuy tTnh hqc ndi rieng va cua co hpc chat luu ndi chung Ngi dung cua dinh lugt dugc phdt bieu nhu sau: "Higu dp sudt giira hai diem A yd B cung nam mgt chdt long cdn bdng cd gia trf bang trgng lugng cda Idioi chdt long chua tmng mot hinh tru thdng dung, ddy co di^n tich bang mgt dam vf va chieu cao bdng dg sdu gi&o hai diem A vd B"[3] NGHIEN CUU & U>IG DUNG 2.5 Djnh lu^t Paxcan Tir bieu thiic (4) ta suy ra: Bieu thuc (5) cho ta thay neu ta tang dp suat tgi diem A PB-PA _ A/^ -Dg K-h^ ~ Ah ' AP = Dg.Ah (5) Ciia chat long dung ttong binh kin khdng bien dgng chiia day chat Idng, chang hgn bang each dung pit tdrig tdc dyng dp luc vdo khdi chat Idng {Hinh 2) thi tdc dung ndy dugc truyen vdo chdt long ^3^ Vi chat Idng khdng nen dugc, D vd Ah khdng ddi nen mgi diem ciia chdt long vd ciia thdnh binh"[l] C H E T A O B Q THf lo la noi de d$t cdc nut cao su (so lugng cdc Id tren ndp thugc vao so ong nghipm diing NGHIDM TU' N H C ' N G dk edm vdo binh, khdng nen NGUYEN L i f U DON GI A N diing qud nhilu Ing nghipm vl 3.1 Cau tao: Bg thi nlu dimg nhilu sg roi mdt) j nghipm gom: - Cdc niit cao su (Hinh 2'c), - Binh thuy tinh (Hinh 2a) tren niit c6 lo d l cdife ong thiiy diing de dgng nirdc Binh cd tinh Phdi gdn cdc niit cao su dgng hinh hgp chir nhdt dugc vdo ndp thgt chdt Cdc nut cao ldm bdng kinh thdng thudng su ndy thudng cd rdt nhieu ttong sudt, khdng mau, kich tiong phdng thi nghipm eua thudc: 0,2mx X 0,15m X 0,45m cdc trudng p h i thdng, (kich thudc b i n Lirf h ii y - Hp thong tao dp Iuc l@n tinh cd the thgy ddi, tiiy theo chat Idng gom: muc dich ciia GV tien + Mdt qud bdng (hode mpt hdnh thi nghiem tren ldp hgc chiec bom tiem thu y) day nhung khdng dugc qua to chinh la bg phan de tao dp hodc qua nhd) Cdc tam thiiy lyc len chat Idng tinh sau cat theo cdc kich + Mgt dogn dng bang cao thudc da chgn chung dugc gdn su hogc lay mdt dogn ciia dng Igi vdi bang keo dan truyen thudc cho benh nhan kinh + Mgt doan dng thiiy tinh - Cac ong thuy tinh (Hinh thang cd ciing kfch thudc vdi 2d) tiet dien nhd gidng dng cao su hogc dng truyen da Hinh (Pg - PA) khdng ddi Ndi cdeh khdc, ttong qud trinh truyen dp luc ndi tten, dp tang dp suat tgi diem A vd diem B la nhu Dieu da dugc nhd bac hpe Paxcan phdt bieu thdnh dinh luat ed ndi dung nhu sau: "Khi mgt chdt long dugc giam kin mgt binh khong biin dgng chiu mot tdc dung tdng dp tir ben ngodi thi tdc dung ndy dugc ^ tmyen den mgi diem cua chdt long vd tdng dp tgi mgi diem Id nhu nhau"[3] Ngi dimg dinh ludt cdn dugc phdt bieu dudi dgng khac nhu sau: "Do tdng dp sudt len mot chdt long chira binh kin dugc truyen nguyen vgn eho Hinh 2c cd hinh dgng vd kich thudc dai ngdn khac nhau, Id noi de cho nudc dang len hodc hg xudng Cd the kiem cdc dng thiiy tinh tu phdng thi nghiem ciia nhd trudng hoae mua tgi cdc trung tam thiet bi trudng hpc - Ndp hop (hm/i 2Z)) dugc lam bang xdp, kfch thudc ciia ndp theo kich thudc cua binh thiiy tinh, nhung luu y phai cdt nap hoi vat mdt chiit thi day vao binh mdi chat vd kin Tren ndp cd khoet cde IL Hinh 2d > Hinh 2e chgn d tten Qua bdng, dng cao su va dogn dng thiiy tinh dugc ndi vdi nhu hinh vg {Hinh 2e) Lap ghep cdc bd phgn (modun) tren lgi vdi ta dugc bd thi nghiem dimg de nghien cuu dinh luat Paxcan nhu hinh ve (Hinh 3) Chuy: * Khi ldp rdp cdc bp phan vdi phdi day nap vao binh, cam dng thiiy tirji vao ndp vd niit cao su vdo ndp cho TAP CHITHIETBI GIAO DUC-SO 89-01/2013 - I S NGHIEN CUtJ & UMG DUNG Hinh that kin, Ak trdnh nudc tir binh trdn ngodi cung nhu khdng tir ngodi vdo binh Dgy cdng kfn thi thf nghipm cdng chinh xdc Neu khdng dgy kin, nudc cdc ong thiiy tinh sc khdng dang len eao nhu nhau, dd thi nghipm se khdng chinh xdc * Cdc mipng dng thiiy tinh chat Idng phai dugc ddt d cac dg cao khac va hudng ve cdc hudng khac (ddi vdi cdc dng cong hodc hinh thudc thg) Neu mipng cdc dng d ciing^ mgt cao va eung hudng ve mdt phia thi viec hinh thdnh djnh lugt se khdng mang tinh tdng quat 3.2 Nguyyen tdc hoat dpng - De tgo mgt dp luc tren mat chat long ta ehi can dung tay bdp nhe vdo qua bdng hogc an nhp cho pit tdng ciia bam tiem chuyen dpng tii tren xudng dudi - Quan sat nudc cdc dng nghiem ta thay nudc dang len cac dng Id nhu Dilu chiing td tdc dyng du^fc truyen den mpi diem ciia chat long vd dp tdng dp tgi mgi dilm Id nhu Chiiy: * N I U nudc dang len cdc dng cd dp cao khong nhu thi phdi kilm tra lai kfn gifta ndp vdi hop, gifta niit vdi ndp vd gifta ong nghipm vdi mit cao su * Dk HS quan sdt nudc dang len cdc ong nghidm dugc rd n6t thi cdn phdi hda them vdo ttong nudc mgt ft bgt mdu -r K ^ T LUAN Tdm lgi dgy hgc, neu moi GV cd thl t^ tgo cdc thi nghipm thay the cho nhitiig thf nghipm cdn thilu vd dem su dyng chiing dgy hpc mgt cdeh hl^u qud, sg tgo dieu kipn cho HS phdt huy dugc mgi ndng lyc vdn cd ciia minh hge tgp, nghien ciru tu dd giiip cdc em tiep thu va hieu bai mgt cdeh chu dpng hon, hp thdng hon vd each sau sac ban Ddi vdi GV, qua vipc che tao cdc dung cy thi nghipm thay the, se giiip cho mdi GV de dang hem tren dudng hinh kien thuc cho HS ttong dgy hgc Thiet nghT, vipc che tao cdc dyng cy thf nghipm thay the cho nhirng thf nghipm cdn thieu la mgt nhipm vy dgy hgc cdn dugc ddt ddi vdi mgi GV vgt If hipn dan^ gidng day d cdc trudng phd thdng hien Tdi H^u t h a m khdo Nguyin The Khdi - Phgm Qui Tu - Lucmg Tdt Dgt - Le Chan Hiing - Nguyin Ngpc Hung - Phgm Dinh Thiet - Biii Trpng Tuan - L6 Trgng Tudng Vat li ldp 10 Nang cao NXB Giao due - 2006 Nguyen Thl Khdi Phgm Qui Tu - Luong Tdt Dgt - Le Chan Himg - Nguyin Nggc Hung - Phgm Dinh Thilt - Biii Trgng Tudn - Lfi Trgng • TAP CHITHIETBI GIAO DUC-50 89-01/2013 Tudng Sdeh gido vien vat If I6p 10 Ndng cao NXB Gido dgc 2006 Luang Duyen Binh Phgm Gia Thjnh Nguyin Xudn Chl - Td Giang - Tr§n Chf Minh - Vu Quang Vgt li ldp 10 Ban co bdn (Sdch thi diem) - NXB Gido dye - 2003 Luang Duyen Binh Phgm Gia Thjnh Nguyin Xuan Chi - Td Giang - Tran Chi Minh - Vu Quang Sach gido vien vgt li ldp 10 Ban co ban (Sdch thi di^m) - NXB Gido dye -2003 Nguyen Huu Minh Co hpc (Sdch cao ddng su pham)NXB Giao d y e - 9 Luong Duyen Binh Vatti dgi cuong tap - Phdn co nhi?t - N X B Gido d y e - 9 Nguyin Vdn Anh - Hoang Vdn Vipt Gido trinh vat Ii dai cuong NXB Dgi hgc su pham Summary In recent yeais, most sdwc^ are equipped with much more laboratory instiumaits in mler to elevate the quali^ of feachii^ and meet tlie inaeasing danandfertbe innovation of tlie country However, practical teaching shows that the lack of laboratoiy instrumoits leads to negative influences on teaching process Therefore, unciastanding and researching to produce AK missing instruments not cxily is a matter of ur^tcy and a meanii^ issue, but also ^ves fevourable ccxiditicnis to teacheis and students in their learning process ...NGHIEN CUU & U>IG DUNG 2.5 Djnh lu^t Paxcan Tir bieu thiic (4) ta suy ra: Bieu thuc (5) cho ta thay neu ta tang dp suat tgi diem A PB-PA... trinh truyen dp luc ndi tten, dp tang dp suat tgi diem A vd diem B la nhu Dieu da dugc nhd bac hpe Paxcan phdt bieu thdnh dinh luat ed ndi dung nhu sau: "Khi mgt chdt long dugc giam kin mgt binh... 2e) Lap ghep cdc bd phgn (modun) tren lgi vdi ta dugc bd thi nghiem dimg de nghien cuu dinh luat Paxcan nhu hinh ve (Hinh 3) Chuy: * Khi ldp rdp cdc bp phan vdi phdi day nap vao binh, cam dng thiiy