So Hn 08

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SOGIAO DUC & DAO TAO

He NOr

Ndm hoc 2008-2009

oEcHfNurHuc

Mdn : VOtIt Ngirythi:26 -Il - 2008 Thdi gian lhm bii: l8Ophft (Dd thi gdm 2 trang)

CAu I (4 di6m)

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Dudi t6c dung cira m6men ngoai luc, mdt brinhxe thu duoc dd thi vAn toc g5c thco thdi gian

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nhu hinh vE. a. Tim gia toc g6c cira b6nh xe trong ciic g i a i d o a n c h u y d n d Q n g(.? , C , -

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b. Tim g6c quav cfia b6nh xe trong suot thdi gianchuyeindQng. $

Hinh I

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c. Trong quii trinh quay chflm ddn ddu,vflt chi chiu mdmen luc ma s6t c5 d0ldn 0,2Nm. Tim mdmenluc phiit dOngkhi vAt quay nhanhddn ddu (mOmenluc ma sdt kh6ng d6r). ('/ (-. CAu II (4 rlidm) Me,t ld xo khi treo vAt M o vi tri cAn bang thi lb xo gifrn 4cm. Kich thich vdt dao d6ng didu ho) theo phuong thing dung vdi bi6n d6 -5cm.Chon goc thdi gian lfc vAt di qua vi tri cAn bAng(lay I = l0 mfs';n' - 10). c trong0,ls ddu tien. 15 ) a. Tim qudngduongvAtdi du-o, b. Vat M nOutrOnc5 dang hinh h0p, khoi luong 3009. Noi v0t vio h0 lb xo gdm L, c6 do crlngk, =180N/mvh L, c
c. Dat vAt thrl hai c6 khoi lugng m= 2009 lOntrOnvAt M, mAt tidp xtic gifra hai vAt ld m[t phangnam ngang. Kich thich h€ dao d6ng bang c6ch truydn cho h0 tt vi tri cAn bang vAn tdc 24,5cmlstheo phuongtring vdi truc cira lb xo. Ta thay hQdao dOngdi6u hoh, h0 so ma sritp gifra hai v0t phii thoi mdn didu ki6n nlo?

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Hinh 2

CAu III (4 itiim) Mdt con l6c don c6 khoi luong m=l0g dao d6ng didu hod tr€n mf,t ddt vdi chu kj' Tt,=0,44(s) r 1,256s.L?iyg = l0nr/s2. a. Tim chidudli criacon l6c. ,.{C'i,,,

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b. Tfch diOncho con l5c tren di0n lugng q = l0-6Crdi dat con l6c vho vilng c6 diOntrudng ddu thing dring thi chu kj'dao ddng ctracon l6c tang lan l,Zldn. Xiic dfnh d6 l6n vir hu6ng cira / )'( ' , l\ dientrudng. ; c. Lliy hai con l5c don cing chidu dli vl khoi luong, t(ch cho chring dien tich q, vd q, rdi dit vdo kh6ng gian dien trubrngddu thangd,ing. Kich thfch hai con l6c tr€n dao d6ng didu hod,do

duocchuki Tr = 5T,,vhT,' =l T,,.Tirnti so 4 7 q,

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CAuIV(4diim) MOt chidc brit bang 96 trong ldng brit hinh brin cdu rdm O. hiin kinh R c
quay.

\ :-., b. Tirn giri tri at d€,v\t namy€nddi vdi brit. . n ' l

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Hinh 3

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CAuV (4 diim)

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Trong thi nghi0m giao thoa trOnmdt chat l6ng, hai ngudn ket hcp cing pha dao d6ng v6i tdn so 40Hzt6c dong lOnmat chat l6ng tai hai didm A vI B c6chnhau l0cm. Tai didm C tron mit chAtl6ng ci{chA doand, = 2lcm v}rcrichB doan dz= l9,5cm s6ng c6 biOnd0 cuc dai. Gifra C vi duongtrung truc Ix cira AB (didm I nam r0n AB) chi c6 mOtddy dao d6ng cuc tidu . a. Tim vAntdc truydn s6ng tr0n mat chAtl6ng.1 q, -rx+_ri,, / r / b. Cd bao nhi€u didm dao dQngcuc dai trOndoanAts? 4 f|

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c. TrOnduong trung truc [x ngudi ta thay c6 didm P gdn I nhAt dao d6ng cing pha v6i ngudn.Tim khoing c6ch PI

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d. Didu chinh cho hai ngudn kdt hqp trOndao dOngnguoc pha nhau. Tr0n dudrngtrdn duongkinh AB c5 bao nhiOudidrn dao dQngvdi bien dQcuc dai? Le

---------He't (Gidm thi khdng gitii thich gi thAm) Ho vh t€n thf sinh :........'!ii,,r,......[.{r.......1.ur1*',.r....... Sdb6odanh:..... !.iJ.. J....;,....

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