b) Write 3 – 4 sentences to describe the first law of thermodynamics and use it to describe what happens when two substances at different temperatures come in contact with each other.

Question

I know the first law states that "energy can neither be created nor destroyed" but I do not understand the second part of the question

Answer 1

Substance A is hot and substance B is cold. They come together. The hot material loses heat and the cold material gains heat but the heat lost - heat gained so heat (energy) is not created or destroyed but relocated (moved around).