1) 1 song co hoc duoc truyen tu diem O theo phuong Ox voi toc do v = 40cm/s. Nang luong song duoc bao toan dao dong tai nguon O co dang: uo = 4cos \(\dfrac{\Pi}{2}t\) (cm)
a) T=? , λ ?
b) Viet phuong trinh song tai diem M: d = OM, uM?. Xac dinh d de dao dong tai M cung pha voi dao dong tai O
c) Biet tai t: uM = 3cm. Xac dinh li do tai M sau khoang Δt = 6(s)