This is the 2175th most frequent Russian word.
воздействие
Influence or impact.
The word 'воздействие' here refers to the effect or influence of one force on another, in this case, heat on metal.
Тепловое воздействие на металл привело к его расширению.
The heat impact on the metal caused it to expand.
In this sentence, 'воздействие' signifies the influence or effect music has on human emotions or mood.
Воздействие музыки на настроение человека интересно изучать.
The effect of music on a person's mood is interesting to study.
Here, 'воздействие' is used to refer to the impact or consequences of activities on the environment.