The incident wave in problem 1 [y = 4 sin (3p t - 6p
x)] and the reflected wave
y = -4 sin (3p t +
6p x) produce a standing wave.

(b)(i) Sketch the standing wave at t = 0s

y = -8 cos3p t
sin6p x
at t = 0, cos 0 = 1
Therefore, y = -8 sin6p x
This is just a negative sine curve with a maximum of 8 and a wave length of 1/3 (Remember
k = 6p = 2p /l)