Question
For the harmonic travelling wave $\text{y}=2\cos2\pi(10\text{t}-0.0080\text{x}+3.5)$ where x and y are in cm and t is second. What is the phase difference between the oscillatory motion at two points separated by a distance of:
$\frac{3\lambda}{4}$(at a given instant of time)
$\frac{3\lambda}{4}$(at a given instant of time)