And one to two sentences describe the relationship between harmonics and resonance frequency in a piano

Answer 1

Harmonics are the higher frequencies that are produced when a piano string is struck. The resonance frequency of a piano is the frequency at which the string vibrates the most, and is determined by the length, mass, and tension of the string. The harmonics of a piano string are related to the resonance frequency because they are higher frequencies that are produced when the string vibrates at its resonance frequency.