A transverse harmonic wave on a string is described by, \(y(x,t) = 3.0 sin ( 36t + 0.018x + {\pi \over 4})\) where x and y are in cm and t in sec. The positive direction of x is from left to right. What is the shortest distance between two successive crests in the wave?

For the travelling harmonic wave, \(y(x,t) = 2.0\ cos\ 2\pi (10t - 0.0080x + 0.35 )\) where \(x\) and \(y\) are in \(\text{cm}\) and \(t\) is in seconds. The phase difference between the oscillatory motion of two points separated by a distance of \(4~\text{m}\) will be:
1. \(0.8 \pi\ \text{rad}\)
2.  \(\pi\ \text{rad}\)
3. \(6.4\pi\ \text{rad}\)
4. \(4\pi\ \text{rad}\)