. Trudng hop 1 k chin L:6c nityA2-Pn
D0 dich chuy6n crha vflt theo dung:
dung:
( n\
rt =-x.> I -\. M)t +i- lana
*("o,', *(t .#),in' o),',.
= -o(r.#).2 + mstand . k m cos2 d*(,* ff)"i,'* 2r a cosz a .1,. #)sin2 a
{Nrr$" x6t. C6c bqn c6 loi gidi dring
Vinh Phric: Hogng Mqnh Thdng, Tq D*c Mqnh, 11A3, LO Tdt Thdng 10A3, THPT chuy6n; Bic Ninh:
Trdn ViQt Long Nguy€n Vdn Bao, 11 Li, THPT chuy6n; Hung YOn: Phqm Dfic Linh, 1l Li, THPT chuy6n; Thanh H6a: Mai Minh Tilng, 1282, THPT
TriQu Son \ Le Bd Sott, I lF THPT chuyOn Lam Son; NghQ An: Nguyln Duc Son, Trdn Vdn Thdng. Trdn Vin-Giai, Nguydn uq Nhu t', A3 K34, THPT chuy€n
Phan BQi Chdu; Ti6n Giang: Tructng Mai Thanh Tdm, 11 Li, THPT chuydn; -Binh
Phu6rc: Nguydn Thdnh Hung, 12Todn, THPT chuyCn Quang Trung.
NGUYEN XUAN QUANG
*gei L2t357. M6t mach diQn gdm mil sii riit
. :. ^ .' ., +,^
l<tn o mang, moi o gom mQt di1n tro va hai vdn k€ (nha hinh vd). Cac vdn kd giiing nhau,
, ,: J J
cdc di€n tro giong nhatt. Mqch di€n dtoc mac
vdo ngu6n dien. C(tp von kO ddu ilAn chi 6Y vd 4Y. Hdy tim
. -)
a) So chi cia cfip von k0 thir hai.
b) T6ng sii chi cua mei v6n k€.
Ldi gifii. Gqi R ve r tuong fng ld <liQn trd cta
chi6c elign trd vi cta v6n k6,, X ld tliQn tro
.t
tuong duong ctia phdn mach diQn cdn lai (hinh du6i). Do sii 6 mpng td r6t l6n n6n 'x +r+R=x r+x Mat kh6c ta c6 h=Iz*Ix i Tt (l) vd(2) suy ra R=r J u,. =Lu,=1v. JJ
56 chi cria cpp v6n k6 thri hai la Zv vd 1V.
J
( 4\ (z 4\
b) Zu, =(o ++)+[z.iJ.[;5J.
D6 ddng thAy rlng (Jn=ZY;
Ut=Ua*Uy, *Uyr= 2Y + 6V + 4V = 12Y.
Ki5t qun cho thAy
rlUr = 12Y; Uyr=