V i t r i v a n sang^tren m a n quan sat x = k XD a X = ax = 0,5 i^im kD Vay chon dap an A Cdu 50: T r e n m o t sgri day c6 song dCrng v d i bifdc song la X Khoang each giuTa h a i n u t song l i e n ke la A.i B 2X D X Giai Khoang each giufa h a i n u t song l i e n ke la — Vay chon dap an A Cdu 51: M o t v a t vkn dang quay quanh m o t true co d i n h xuyen qua vat Cac d i e m t r e n v a t rSn (khong thuoe true quay) A CO eung gia toe goc t a i cung m o t thori d i e m B CO eung toe d a i t a i cung m o t thcfi d i e m C quay di/gfc nhOfng goc khac t r o n g cung m o t khoang thofi gian D CO toe goe khae t a i eung m o t thc?i d i e m Giiii Cac d i e m t r e n v a t r ^ n (khong thuoe true quay) A co eung gia toe goe t a i C l i n g m o t thcfi d i e m Vay chon dap an A Cdu 52: M o t t h a n h cuTng, nhe, chieu dai 2a T a i m i dau ciia t h a n h CO gSn mot v i e n h i nho, k h o i luong cua m i v i e n h i la m M o m e n quan t i n h cua he ( t h a n h va cac v i e n hi) doi vdri true quay d i qua t r u n g d i e m cua t h a n h va vuong goc v d i t h a n h la A m a l B -ma^ C m a l D -vaa? Giai Ta co: I = ma^ + ma^ = 2ma^ Vay chon dap Cdu 53: an A B i e t dong n&ng tiicfng doi t i n h cua m o t h a t b a n g nang lUcfng n g h i cua no Toe cua h a t ( t i n h theo toe a n h sang ehan k h o n g c) b ^ n g A.ic GA\i tilt 04 thi TS DH, CD Mon Vat I 189 Ta CO E = Eo + Wd = 2Eo Suy r a : V rtioC- GiSi mc^ = 2moC^ = 2moC^ => - = 1- - ^ V = c Vdy chpn dap an C Cdu 54: T a i m a t chat l o n g c6 h a i nguon p h a t song k e t hgfp S i va S2 dao dong theo phifcrng vuong goc v d i m a t chat l o n g c6 cung phi/cfng t r i n h u = 2cos40 7it ( t r o n g u t i n h bSng cm, t t i n h b a n g s) Toe dp t r u y e n song t r e n m a t chat l o n g l a 80cm/s G o i M l a diem t r e n mSt chat l o n g each S i , S I a n Itfcft l a 12cm va 9cm Coi b i e n cua song t r u y e n tCr h a i nguon t r e n den d i e m M l a k h o n g doi P h a n tuf chat long t a i M dao dong v6i b i e n l a A V c m B V c m C cm D cm Giai Biidc song X = —• = — ^ f 20 = cm Song t r u y e n tCr S i va S2 tcSi M c6 bieu thufc: •VIM = 2cos t - 27t.d, ; U2M = 2cos - B i e n song t a i M : A M = 4cos 7r(d,-d,) I- 27t.d, \ X = |4cos 371 = V cm Vdy chgn dap an B Cdu 55: T r o n g so cac hat: proton, anpha, t r i n i vk dcfteri, hat so cap la A t r i n i B dorteri C anpha D proton Giai Chgn dap an D: P r o t o n Cdu 56: K h i n o i ve m o t v a t dang dao dong dieu hoa, p h a t bieu nao sau day dung? A Vector gia to'c cua v a t d o i chieu k h i v a t c6 l i ctic d a i B Vector v a n toe va vectcf gia toe cua v a t cung chieu k h i vat chuyen dong ve p h i a v i t r i can b a n g C Vectcf g i a toe cua v a t luon hirdtng r a xa v i t r i can b&ng D Vector v a n toe va vectcf gia toe cua v a t cung chieu k h i vat chuyen dong r a x a v i t r i can bang Giai Chi tiet 90 thi TS DH, CO M6n VSt li Giai Vay chgn dap an B: K h i v a t chuyen dong n h a n h dan Cau 57: T r o n g song dien tijf, dao dong cua d i e n t r i l n g v& cua tCr tnfcfng t a i m o t diem luon luon A ngifoc pha B lech pha ^ C dong pha D lech pha ^ Giai Dao dong cua dien trtfdng va cua tCf trifdng t a i m o t d i e m luon luon dong pha Vay chgn dap an C Cdu 58: Chieu bufc xa d i e n ttf c6 bilcSc song 0,25 fim vao catot cua mot te bao quang dien c6 gidri h a n quang d i e n la 0,5 ^ m Dong n a n g ban dau ctfc d a i cua electron quang dien la A 3,975.10-2°J B 3,975.10-"J C 3,975.10-'^J D 3,975.10-i'J Giai Ta c6: ^ = ^ + Waon.ax => W^o^ax = ^ - ^ = 3,975.10-^^J Vdy chgn dap an C Cdu 59: M o t v a t r a n dang quay n h a n h dan deu quanh m o t true co dinh xuyen qua v a t M o t d i e m t r e n v a t rSn (khong thuoc true quay) c6 A vectof gia toe t i e p tuyen hifdfng vao t a m qui dao cua no B I6n gia toe tiep tuyen k h o n g doi C vectcf gia toe t i e p tuyen nguTOc chieu vdri chieu quay cua no d m o i th&i diem D lorn gia toe tiep tuyen t h a y doi GiSi Chgn dap an B Cdu 60: M o t v a t r a n quay quanh dan deu tCf t r a n g t h a i n g h i quanh mot true CO d i n h xuyen qua v a t Sau 4s dau t i e n , v a t r S n dat toe goc la 20 rad/s T r o n g thcfi gian do, mot diem thuoc v a t rSn (khong n ^ m t r e n true quay) quay difOc mot goc c6 16'n b k n g A 40 r a d B 10 r a d C 20 r a d D 120 r a d Giai Chgn dap an A Giaichitigt - = 1- - ^ V = c Vdy chpn dap an C Cdu 54: T a i m a t chat l o n g c6 h a i nguon p h a t song k e t hgfp S i va S2 dao dong theo... can b&ng D Vector v a n toe va vectcf gia toe cua v a t cung chieu k h i vat chuyen dong r a x a v i t r i can bang Giai Chi tiet 90 thi TS DH, CO M6n VSt li Giai Vay chgn dap an B: K h i v a t