Thiết kế bài giảng vật lý 12 nâng cao (tập 1) phần 1

TRAN THUY HANG HA DUY£N TUNG NANG CAO TAPMOT NHA XUAT BAN HA NOI ,,,i-'ft TRAN THUY H A N G « - H A DUYfiN TUNG •« THIET KE BAI GIANG cm T^rtlSMH ^ "iHt NANG CAO - TAP NfiA XUAT BAN HA NOI .ai not ddu Thie't ke bai giang Vat li 12 nang cao dvroc viet theo chifdng trinh sach giao khoa m6i ban hanh nam 2006 - 2007 Sach gidi thif u m6t each thi§'t ke bai giang VSt li nang cao theo tinh than doi mdi phifdng phap day - hoc, nham phat huy tinh tich ciTc nhan thiic cua hoc sinh Ve noi dung : Sach bam sat noi dung sach giao khoa VSt li 12 theo chifdng trinh nang cao O moi tie't, sach chi ro muc ti§u ve ki^'n thiic, ki nSng, c»c c6ng viec chuan bi ciia giao vi^n va hoc sinh, cac phtTOng tien ho trd giang day can thie't, nham dam bao chat Iifdng tufng.bai, timg tie't len Idp Ngoai sach co md rong, bo sung them m6t sd' ndi dung lien quan tdi bai hoc bang nhieu hoat dong nham cung cS'p them tu" lieu d6 cac th^y, co giao tham khao vSn dung theo do'i ttfdng hoc sinh tiing dia phiTdng Ve phifdng phap day hoc : Sach diTdc tri^n khai theo hvrdng tich cue hoa hoat ddng cua hoc sinh, lay cd sd cua moi hoat dong la nhiing viec lam cua hoc sinh dudi su" htrdng d i n , phvi hdp vdi dac trvmg mon hoc nhiT : thi nghif m, thao luan, thu'c hanh, nham phat huy tinh doc lap, tu" giac cua hoc sinh Dac bi^t, sach rat chii khau thu'c hanh timg bai hoc, ddng thdi ciing chi ro tung hoat ddng cu thg cua giao vien va hoc sinh mdt tiS'n trinh day hoc, coi day la hai hoat ddng ciing ca hoc sinh va giao vign la chu the Chiing tdi hi vong cud'n sach se la mdt cdng cu thie't thUc, gop p h i n hd trd cac thiy, cd giao giang day mdn Vat li 12 viec nang cao hif u qua bai giang cua minh Cac tac gia CHi/ONG DONG Ll/C HOC VAT RAN • • • • BAII CHUYEN D N G QUAY CUA VAT RAN QUANH M T TRUC c DESfH I - MUC TifiU V^" kien thtic - Hoc sinh hieu duoc khai niem vat rdn va chuyen ddng tinh tien cua vat ran la gi - Hoc sinh hieu duoc khai niem toa dp goc (p - Xay dung dupe cac cdng thiic tdc goc co, gia tdc gdc y - Nam viJng cac cdng thiic lien he giiJa tdc gdc va tdc dai, gia tdc gdc va gia tdc dai ciia mot diem tren vat rSn - Xay dung dupe cac phuong trinh ddng hpc ciia chuyen ddng quay - Van dung dupe eac cdng thiic ciia chuyen ddng quay deu, quay bie'n d6i diu de giai cac bai tap don gian Ve ki nang - Ren luyen cho hpc sinh kT nang sii dung phuang phap tuong tu de xay dung cac khai niem, cdng thiic cua chuyen ddng cua vat ran II - CHUAN BI Giao vien - Ve hlnh 1.1, 1.2, 1.4, 1.6 trdn gia'y kho AQ Hoc sinh - On tap lai phin ddng luc hoc chat diem b Vat li Idp 10 THPT Ill - THifiT Kfi' HOAT D N G DAY - HOC Hoat d o n g cua hoc sinh Tror giiip cua giao vien Hoat dong Kiem tra, chuan bi dieu' kien xuat phat Dat van de GV neu cau hdi kiem tra kie'n thiie cu - Neu khai niem vat ran - Chuyen ddng tinh tien la gi ? HS suy nghT ca nhan tim cau tra Idi HS nhan thiic dupe van de cua bai hpc - Viet phuong trinh chuyen ddng cua vat chuyen ddng thing bie'n doi deu Viet cdng thiic van tdc cua vat dd Dgt vdn de : Idp 10, chiing ta da xac dinh quy luat chuyfin ddng ciia vat ran chuyen ddng thang bie'n doi deu Bai hpc chiing ta di sau tim hieu va xac dinh quy luat chuyen ddng, tim mdi lien he giOa eac dai lupng dac trung cho chuyen ddng quay cua vat ran quanh true CO dinh Hoat dong Tim hieu khai niem toa goc HS quan sat hinh ve 1.1 tren kho gia'y AQ, suy nghT ca nhan tim eau tra Idi — Mdi diem tren vat vach mdt dudng tron nam mat phang vudng gdc vdi true quay, n kinh bang khoang each tir di6m de'n true quay, tam ciia quy dao nam tren true quay - Mpi diem ciia vat deu quay duoc cung mdt gdc cung mdt khoang thdi gian GV neu cau hoi de HS tim hieu khai niem toa dp gdc: - Xet.mdt vat ran bat ki quay quanh mdi tmc Az t d dinh (Hinh 1.1 SGK) Hay cho bie't dac diem ciia quy dao cua mdt di6m tren vat ran vat ran chuyen ddng va gdc quay ciia cac diem tren vat ran? Tro g i u p ciia giao vien Hoat d o n g cua hoc sinh : GV thdng bao: HS tie'p thu, ghi nhd ; - Quan sat tren hinh ve, vi tri cua vat tai mdi thdi diem se dupe xac dinh bang mdt gdc (p giira mat phang ddng P gin vdi vat va mdt mat phing cd dinh PQ Gdc 0 Hoat dong Xay dung khai niem toe goc trung binh va tdc goc tiic thdi GV neu cau hdi de HS xay dung khai niem tdc dp gdc: HS thao luan chung toan Idp j - Khi vat rin quay, su bie'n thien theo thdi gian ciia (p the hien quy luat chuyen ddng quay cua vat rin Hay tim mdt dai lupng dac trung cho miic dp quay nhanh hay cham eiia vat rin Dai lupng dd dupe xac dinh nhu the nao ? GV neu cae cau hdi gpi y: - Dai lupng dac trung cho miic dp | quay nhanh hay cham dupe xac : - Trong chuyen ddng thing, dai lupng nao dac trung cho chuyen ddng nhanh hay cham ciia vat ? Dai lupng dd dupe xac dinh nhu the nao? dinh bang thuong so —^ • At ' : - Tuong tu, chuyen ddng quay, ta cd the tim mdt dai lupng dac trung cho miic dd quay nhanh hay cham ciia vat rin dupe khdng ? - thdi diem t, toa dp gdc ciia vat la g) thdi diem t +At, toa dp gdc ciia vat la Hoat dong ciia hoc sinh Tror giup cua giao vien (p + A(p, dai lupng dac trung cho miic dp quay nhanh hay cham ciia vat rin dupe xac dinh nhu the nao ? GV thdng bao: - Dd chinh la tdc dp gdc trung binh j C0f^J = cua vat rin khoang thdi At gian At HS thao luan chung toan Idp - Tdc dp gdc tiirc thdi d mdt thdi diem t duoc xac dinh bing gidi han - GV yeu cau HS xay dung cdng thiic xac dinh tdc dp gdc tiic thdi va cho biet don vi cua tdc dp gdc ciia ti sd —^ A / tien dan tdi At co = hm i^0 At - Don vi ciia tdc dp gdc la rad/s Hoat dong Xay dung khai niem gia tdc goc trung binh va gia tdc goc tiic thoi GV neu cau hdi de HS xay dung khai niem gia tdc gdc: - Hay tim mdt dai lupng dac trung cho su bie'n thien nhanh hay cham ciia tdc dp gdc Dai lupng dd dupe xac dinh nhu the nao? HS thao luan chung toan Idp - Dai lupng dac trung cho su bie'n thien nhanh hay cham cua tdc dp gdc dupe xac dinh bing thuang so Aco At GV neu cac cau hdi gpi y - Trong chuyen ddng thing, dai lupng nao dac trung cho sir bie'n thien nhanh hay cham ciia van tdc ? Dai lupng dd dupe xac dinh nhu the nao ? - Tuang tu, chuyen ddng quay, ta ed the tim mdt dai lupng dac trung cho Trd giiip cua giao vien Hoat dong cua hoc sinh su bie'n thien nhanh hay cham ciia tdc dp gdc dupe khdng ? - O thdi diem t, vat cd tdc dp gdc la co O thdi diem t + At, vat cd tdc dd gdc la (o + Ao) dai lupng dac trung cho sir bie'n thien nhanh hay cham cua tdc dd gdc dupe xac dinh nhu the nao? GV thdng bao: - Dd chinh la gia tdc gdc trung binh Ao) Yi^ = HS thao luan chung toan Idp - Gia tdc gdc tire thdi d mdt thdi diem t dupe xac dinh bing gidi han , , Aft) , , » cua tl so -J.- , , ,, , cua vat ran khoang thai At gian At - GV yeu cau HS xay dung cdng thiic xac dinh gia tdc gdc tiic thdi va cho bie't don vi cua gia tdc gdc , r, A r tien dan tOi At = Hm hay y = coit) ,v->o At -) - Dan vi cua gia tdc gdc la rad/s Gia tdc gdc tiic thdi ciia vat rin quay quanh mdt true d thdi diem t la dai lupng dac trung cho su bie'n thien ciia tdc dp gdc d thdi diem dd va dupe xac dinh bang gdi han , , ^, Ao) , , ,.- , _ cua tl so A t tien dan toi At Hoat ddng Xay dung cac phuong trinh dong hoc ciia chuyen ddng quay GV yeu cau HS phat bilu khai niem gia tdc gdc GV neu cau hdi de HS xay dung phuang trinh chuyen ddng ciia vat rin quay deu: Hoat dong cua h9c sinh Trg giup cua giao vi^n - Trong trudng hpp tdc dd gdc ciia vat rin khdng doi theo thdi gian thi chuyen ddng ciia vat rin la chuyen ddng quay d6u Toa dp gdc ciia vat d thdi diem / dupe xac dinh nhu the nao ? HS thao luan chung toan Idp GV neu cac cau hdi gpi y - Hay neu su tuang ling giOa cac dai lupng gdc chuyen ddng quay va cae dai lupng dai chuyen ddng thing? - Viet phuong trinh chuyen ddng ciia vat chuyen ddng thing deu Tuong tu rin quay diu la : (p = (pQ + cot, nhu vay chiing ta cd the vie't dupe dd q)Q la toa dp ban dau luc f = phuang trinh chuydn ddng cho vat chuyfin ddng quay diu nhu the nao ? Phuong trinh chuyen ddng ciia vat GV neu cau hdi de HS xay dung cac cdng thiic chuyen ddng quay bie'n doi deu: - Trong trudng hpp gia tdc gdc ciia vat rin khdng doi theo thdi gian thi chuyen ddng ciia vat rin la chuyen ddng quay bie'n doi deu Hay vie't cdng thiic xac dinh tdc dp gdc ciia vat d thdi diem t, phuang trinh chuyen ddng eiia vat rin, cdng thiic ddc lap vdi thdi gian chuyen ddng quay HS thao luan chung toan Idp - Cdng thiic xac dinh tdc dp gdc ciia vat chuyen ddng trdn bie'n doi deu tai thdi diem / la : co = coQ + yt 10 GV neu cac cau hdi gpi y: - Viet cdng thiic xac dinh van tdc ciia vat chuyen ddng thing bie'n doi deu tai thdi diem t, phuong trinh chuyen ddng eiia vat va cdng thiic lien he giira van tdc, gia tdc va dp ddi Hoat dong cua hoc-sinh Trd giup cua giao vien - Phuang trinh chuyen ddng quay bie'n ddi diu : - Tuong tu cac cdng thurc cua chuyen ddng thing bie'n ddi deu, hay vie't cac cdng thiic cua chuyen ddng quay 0) - Neu tdc dp gdc giam dan theo thdi gian thi chuyen ddng quay la cham din ir D 0,25 cm Cau 15 Dao ddng nao dudi day khdng phai la dao ddng tit dan ? A Dao ddng cua day dan lay ngdn tay bat vao B Dao ddng cua Id xo giam xdc ciia d td d td qua d ga 113 C Dao ddng cua eon lie don keo qua nang khdi vi trf can bang rdi tha D Dao ddng ciia qua lie eiia ddng hd qua lie treo tudng Cau 16 Dao ddng cudng biic cd nhiing dac dilm nao dudi day ? Dao ddng cudng hire la dao ddng cd dang sin Tin so cua dao ddng cudng biic bang tin sd cua ngoai luc Bien dp ciia dao ddng cudng biic ti le vdi bien dp cua ngoai luc A chi B c h i C chi D ca 1, 2, I I - B A I TAP T U LUAN Bai Con lie Id xo treo thing diing gdm vat cd khd'i lupng m = \kg va\b xo cd dp Cling k = lOON/m Keo vat khdi vi trf can bing mdt doan X = 2cm rdi truyin cho nd van tdc v = 20cmls theo chilu duang cua true 2 toa dp (dpc true Id xo) Cho g =TT = 10mA a) Xac dinh dp dan ciia Id xo vat d vi trf can bing b) Viei phuang trinh dao ddng cua lie Id xo Bai Mdt ddng hd qua lie ed lie nhu lie don Dua ddng hd xudng day mdt cai gieng cd dp sau 800m Biei ring ban kfnh cua Trai Dai 7? = 6400^m Ddng hd chay nhanh hay cham ? Tfnh thdi gian ddng ho chay sai ddm Coi ring nhiet dp d dudi gieng khdng thay ddi DAPANDSI I - BAI TAP TRAC NGHIEM Cau hdi nhieu lua chon B D B A D C C C 10 11 12 13 14 15 16 A D B B A C D D Cau Cau 114 n - B A I TAP T U LUAN Bai a) Khi vat d vi trf can bing thi trpng luc tic dung vao vat can bing vdi luc dan hdi, suy : mg = kAl => A/ = •^ = yt = 6,1m 100 b) Chpn gdc thdi gian r = la liic truyin cho van van tdc v = Imis, ta se cd : x(0) = Acos(p = v(0) = -co A sin 9? = 20 > ; vdi (0 = J— = / Vm V1 Ta cd he phuang trinh : J^cos^ = J.4cos^ = [-o)Asm(p = 20 - J s i n ^ = (2) = Orad I s (1) TT Chia ve' vdi ve' ciia hai phuong trinh ta dupe : tan^? = - 3TT Theo (2), dl van tdc v > thi (p = — thay vao (1) ta duoc A = 2v2cm Vay phuang trinh dao ddng dilu hoa eiia lie la : = 2V2 cos So,-^^ icm) Bai a) Gpi gQ la gia tdc trpng trudng tren mat dit, g2 la gia tdc trpng trudng d dudi dp sau h Six dung dinh luat van vat ha'p din ta tim dupc bilu thirc lien he : g] = gQ h] R) Chu ki dao ddng cua lie ddng hd d tren mat dat va d dudi day gieng lin luat la : T]=2TT /—L — va go TO =2TT j— ^1 115 Ta tha'y - ^ > => 72 > 7j => ddng hd chay cham ^1 Sau mdi chu ki ddng hd chay cham : AT = T2-T] Sau (s) ddng hd chay cham At = V / J = -^ -1 = — T] T] 2R h Suy thdi gian ddng hd chay sai r(s) la: [At)t = — 27? Suy thdi gian ddng hd chay sai mdt dem la : (Ar)r =-^.24.3600 = 5,4(5) 27? BlSUDI^MD^l I - BAI TAP TRAC NGHIEM 0,25 dilm/cau x 16 cau = dilm H - B A I TAP TU LUAN Bai (3 dilm) Xac dinh gia tri Al 0,5 dilm Xac dinh gia tri co dilm Xac dinh gia tri cp, A dilm Viei phuang trinh dao ddng 0,5 dilm Bai (3 dilm) : 0,5 dilm Viei bilu thii'c g] = go Rj Lap tl so - ^ « + — > T : dilm 27? Xac dinh thdi gian ddng hd chay cham sau Is : dilm Xac dinh thdi gian ddng hd chay cham sau Ingay: 0,5 dilm 116 D£2 I - BAI TAP TRAC NGHlfeM Khoanh trdn trudc dap an ma em lira chgn (Chu y : moi cdu chi duac lua chgn mdt ddp dn) Cau Kei luan nao cac kei luan sau day diing ndi vl tan sd ciia mdt vat dao ddng tuin hoan ? Tin sd cua dao ddng tuin hoan la A so dao ddng toan phin thuc hien dupe mdt chu ki B sd dao ddng toan phin thuc hien dupc mdt giay C sd dao ddng toan phin thuc hien dupc mdt khoang thdi gian bing nira chu ki D sd dao ddng toan phin thue hien dupc ca qua trinh dao ddng ciia vat Q Cau Mdt lie don dao ddng tuin hoan nhu hlnh ben Chu ki dao ddng tuin hoan ciia lie la khoang thdi gian vat nang chuyin ddng A tir ^ ^ O ^ B B tir ^ -^ O C.tix A^O^B-^0 D.tiiA-^O-^B^O = # • A .o A • lawts^.^-^s Cau Vat dupc gin vao mdt Id xo thuc hien cac dao ddng dilu hoa vdi tin s o / The' nang bie'n dang dan hdi ciia Id xo , / A thay ddi vdi tan sd — B thay ddi vdi tin s o / C thay ddi vdi tin sd / D khdng thay ddi Cau Mot vat dao ddng dieu hda theo phuang ngang tren doan MN = 8cm vdi CO = 20rad/s Gia sir tai thdi diem / = vat d vi tri cd li dp cue dai (-I-) thi cho den liic t = TT 130s sau vat di dupe quang dudng dai 117 A 2cm B 4cm C 6cm D 8cm Cau Xet dao ddng nhd cua eon lac don, ket luan nao sau day sai ? A Phuang trinh dao ddng la s = S^^ sin(0 , ^ ^ ' =^\ ^ chon (p = A • a /-**^ sin^ = -coAsincp = (**) ^' Thay cp = vao (*), ta cd A = 2cm Vay phuang trinh dao ddng cua vat la x = 2co55;;rr icm) b) Tai vi trf can bing, ta cd -I-Van tdc cua vat : \v\ = co\A -x = COA = 5TT.2 = \0TT cmls + Gia tdc cua vat : a = -co x = - Tai vi trf each vi trf can bing mdt doan a =lcm + van tdc eiia vat : Ivl = 0)\A -a I I = 5v3;r cmls + Gia tdc cua vat: a = (y a = 2,5mI 121 Bai Ap dung cdng thiic A^ = A] +AI + 2AIAI cos[cp2 -cp]) = 3^+3^+2.3.3.cos=> ^ = 3N/2 Ap dung cdng thiic : tancp= A^ sin (P\+ A-, sin cp-, —• — TT ^-^ = = > ^ = — A] cos cp] + A-i cos cp2 vay phuang trinh dao ddng ciia vat la : x = 3v2 sin(2;rr H—)icm) BliuDliMDi2 I - BAI TAP TRAC NGHIEM 0,25 dilm/cau x 16 cau = dilm n - B A I TAP TU LUAN Bai (4 dilm) Xac dinh gia tri o 0,5 dilm Xac dinh gia tri A dilm Viei phuang trinh dao ddng 0,5 dilm Xac dinh gia tri v tai VTCB 0,5 dilm Xac dinh gia tri a tai VTCB 0,5 diem Xac dinh gia tri v each VTCB doan a 0,5 dilm Xac djnh gia tri a each VTCB doan a 0,5 dilm Bai (2 diln,) Xac dinh gii tri A 0,5 dilm Xac dinh gia tri cp I dilm Viei phuang trinh dao ddng 0,5 dilm 122 [...]... —, thay • R • (2) ,ox va- rut ' ra : Trr = -^ ly = -—• la • '• : vao : R R^ j Thay T vao (1) ta dupc : ma la - ma ; R^ mg m+ 1 1 -^ R- , 1 \+ ^ r- mR^ 1 \ • ; Hoat dong 5 Cling cd bai hgc va dinh hudng : nhiem vu hoc tap tie'p theo - GV yeu eau HS lam viec vdi bang 2 .1 SGK dl tim sir tuong tu giira hai phuang 21 Hoat d g n g ciia hgc sinh HS lam viec chung toan Idp Trg giiip cua giao vien trinh ddng... vl nha lam cac bai tap cdn lai trong SGK - On lai eac kie'n thiic vl ddng nang va dd bie'n thien ddng nang da hpc d Vat 11 10 THPT PHIEU HOC TAP Cau 1 Mdt vat cd mdmen quan tinh 0 ,12 kg.m^ quay diu 10 vdng trong \,%s Mdmen ddng lupng ciia vat cd dp Idn bing A 4 kg.m^ls B 8 kg.m^ls C 13 kg.m^/s D 25 kg.m^/s Cau 2 Hai dia trdn cd mdmen quan tinh /, va I2 dang quay ddng true va eiing chilu vdi tdc dp gdc... hpc •• tap dl lam bai tap 1 HS suy nghT ca nhan, sau dd thao ; luan nhdm va dai dien nhdm len ; bao cao kit qua ; Ap dung dinh luat II Niu-ton cho ; chuyin ddng tinh tiln cua thiing ; nude, ta cd : ; mg-T = ma (1) Ap dung phuang trinh ddng luc • hpc cho chuyin ddng quay cua vat ; hinh tru, ta cd : ; M = TR= l.Y (2) : GV neu cac cau hdi gpi y: - Viet phuang trinh dinh luat 11 cho thiing nude - Viet phuang... vdi i tana = - ^ = ^ - a, Y • «« CO ; 12 ; i Trg g i u p ciia giao vien Hoat d o n g cua hoc sinh 1 1 Hoat dong 7 Cling cd bai hpc va djnh hudng nhiem vu hoc tap tiep theo GV yeu cau HS lam viec vdi phieu hpc ; tap; - Yeu cau HS dn tap lai eac kie'n thii'c ; vl: mdmen lire, phuong trinh ddng lire ; hpc ciia chat dilm, y nghTa cua khdi ;lupng PHIEU HOC TAP Cau 1 Mdt canh quat dai 20cm, quay vdi tdc... ( y - 28 1] Q)2 + l2(0\ /,+/, "(oTijjH;); /, hii? «] \ 'llll;, ""/, 1\ ... rad/s D 11 rad/s Cau 16 Mdt vien da mai quay diu cii phiit quay dupe 12 0 00 vdng Van tdc gdc cua nd tinh bing rad/s A.41S ,1 rad/s B 415 ,5 rad/s C 412 , 3 rad/s D 405,4 rad/s 1 - B A I TAP T U LUAN... ciia he dd 44 DAPAND^I I - BAI TAP TRAC NGHlfeM Cau hdi nhieu lua chon B B A D B D C A 10 11 12 13 14 15 16 A D B C B B A Cau Cau B II - BAI TAP T U LUAN Bai a) Ta cd co = Q)Q + yt-0 + yt^>y-... cua ghep nim P DAFAND^2 I - BAI TAP TRAC NGHIEM Cau hdi nhieu lua chon B C D C B B D D 10 11 12 13 14 15 16 A B A C B C A A Cau Cau 50 n - B A I TAP T U LUAN Bai Chpn md'c thdi gian r = tai thdi