Amechanical wave is created when a medium or moves back and forth or up and down

The correct word for the blank is 'oscillates'

" a mechanical wave is created when a medium oscillates , or moves back and forth or up and down

Explanation:

When the matter oscillates or vibrates it transfers energy through the medium in the form of wave which termed s mechanical wave.For example: Sound wave,slinky waves, water waves are the examples of mechanical waves.

So, " a mechanical wave is created when a medium oscillates , or moves back and forth or up and down

i think they are all correct

explanation:

they seem good