An orchestral performance is ful of physics concepts. The design of the hall deals with acoustics - how waves interact with different surfaces and how to make sure that there are no dead spots in the hall.
The sounds produced by all of the instruments are a result of standing waves of various frequencies. The musicians vary the frequency by changing the lengths of the standing waves being produced. Thus, for example, a person playing a stringed instrument changes the pitch by changing the length of the string as they move their hand up or down.
Because there are a variety of instruments playing at any given time there is the potential for both positive and negative interference. Interference occurs when two or more waves are in the same place at the same time. If the crests of two waves come together there is positive inteference and the sound is louder while if the trough of one wave combines with the crest of another wave the loudness is reduced or cancelled out.
Two instruments playing almost the same note result in beat frequencies. Beat frequencies are used when the orchestra is tuning their instruments - the members of the orchestra know they are in tune when the beat frequencies are eliminated.
Reflection - bouncing of waves off a surface - and refraction - the bending of sound waves around surfaces are also physics concepts present in the performance.