A stationary wave travels along a stretched string. Part of this wave at a particular
instant is shown.
The period of vibration of this wave is 20 ms. Sketch the stationary wave 10 ms after the instant shown.
The Attempt at a Solution
I think the wave will be reversed after moving half period. Let say the equation of the wave is sin, then after moving for 10 ms the equation will be - sin. But the answer says that the graph will be horizontal line. I don't understand how it can be horizontal line only (I assume the answer means that all the amplitude is zero)