# What happens to the energy when two waves completely interfere destructively? [duplicate]

this question has been asked many times and none seem to completely answer or i am unable to understand the answers

So let us consider two mechanical transverse waves traveling in opposite directions on a string let us further consider the moment where they interfere destructively

at the moment when they interfere we see the string as if nothing happened then what happened to energy ? where does it "hide"?

Well in the case of a mechanical wave (as you described), you cannot freeze the wave in one instant in time and then ask what the energy is, you lose this way the information about the velocity (and hence kinetic energy). The potential energy will be $$0$$ but the temporal derivative of the wave, which is connected to the velocity (and its square is connected to the kinetic energy) won't be.
This is exactly like a single particle attached to a spring, and asking where the energy is when the particle is at $$x=0$$, it is in the velocity.