1, the vibration equation is y=Acos(ωt+φ), and it can be seen from the figure that A is 0.2m, so it is necessary to calculate ω and φ. According to the displacement y=0 when t=0 is known, φ = 90 or-90 can be calculated. Combined with the downward vibration at this time, φ = 90. T 1 and t2 are both peaks, so T2-t1= (n+0.25) t.

T2-t 1 = (n+0.25) t

2. According to the wave equation, it is easy to calculate that the wavelength is 0.6m, and angular velocity, wavelength and initial phase can be substituted (positive sign is right propagation, negative sign is left propagation).