Trong triforng hcfp nay, dai liftfng thay doi la: A.. momen dong lifgrng cua vat doi vdfi true do.. G\k\ Vat r a n quay quanh mot true co dinh difdfi tac dung eua momen lire khong doi v
Trang 1Gi^i
V i con lac dcfn va con Ike 16 xo dao dong dieu hoa vdri cung t a n so
nen chung cung chu k i :
T, = 271 - = T , =271 - ^ - = - = > m = k - = 1 0 - - — = 0,5kg
g V k g k g 9,8
Vdy chqn dap an B
Cdu 57: M o t vat r ^ n quay quanh mot true co' dinh dvCdi tac dung eua
momen life khong doi va khae khong Trong triforng hcfp nay, dai liftfng
thay doi la:
A momen quan t i n h eua vat doi vdri true do
B momen dong lifgrng cua vat doi vdfi true do
C khoi liTgfng cua vat
D gia toe goe cua vat
G\k\
Vat r a n quay quanh mot true co dinh difdfi tac dung eua momen lire
khong doi va khae khong t h i momen dong lifofng cua vat doi vdri true
do thay doi
Vdy chon dap an B
Cdu 58: M o t nguon phat song ca dao dong theo phUcJng t r i n h :
u = 4cos 47rt-71 (em) Biet dao dong t a i hai diem gan nhau nhat tren
It
cung mot phtTcfng truyen song each nhau 0,5 m eo do lech pha la —
Toe do truyen cua song do la: *
A 1,0 m/s B 6,0 m/s C 2,0 m/s D 1,5 m/s
Giai
Do lech pha giCifa hai diem: A(p = 27i — = — =>X, = 6d = 6.0,5 = 3m
X 3 Theo de bai: co = 47i f = 2Hz
Toe do truyen song: v = = 3.2 = 6(m/s)
Vdy chqn dap an B