Giai T a c o : T = 27rs/LC n e n t = - V L C = - N a n g li/cfng tCf triTofng la: W = Wo sin-cot = - C U ^ s i i r ~ - Vgy chgn dap icil,i an D Cdu 57: M o t dong co' dien xoay chieu k h i boat 'long b i n h thiXc^ng vdri dion ap hieu dung 220 V t h i sinh cong suat c O h o c la 170 W Biet dong ca C O he so cong suat 0,85 va cong suat toa nhifit t r e n d a y quan dong ccf la 17 W Bo qua cac hao p h i khac, ciTong dong dien CLTC dai qua dong co" l a : A A B A D V2 A C A Giai Cong suat t i e u t h u cua dong cd: P = P i + P2 = 170 + 17 = 187 W Cu'drng hieu dung qua dong ccf: Ucoscp 200.0.85 ^ ^ Cu'o'ng dong dien eye d a i : I Q = l\l2 =42 Vay chgn dap (A) an D Cdu 58: T r o n g chuyen dong quay cua v a t r a n quanh m o t t r u e eo dinh, momen quan t i n h ciia v a t doi v d i true quay A phu thupc toe goc cua v a t B t i le v d i gia toe goc cua vAt C phu thuoc v i t r i ciia v a t doi vdfi true quay D t i le v d i momen life tac dung vao vat Giai T r o n g chuyen dong quay cua v a t rSn quanh mot true c o d i n h , momen quan t i n h cua v a t doi vori true quay phu thuoc v i t r i ciia v a t doi vdfi true quay Vay chgn dap an C Giai Chi tiet de thi TS BH CD Mon Vat i 82