1. x = 5 sin(\(\frac{2π}{3}\)t), when we compare this equation with standard S.H.M, x = a sin wt.
We get wt = \(\frac{2π}{3}\)t

2. y = a sin wt
2.5 = 5 sin w × t

Time taken to travel 2.5 from the mean position is 0.25 sec. Hence time taken to travel 2.5 cm on either side of the mean position is 0.5 sec.