Final answer:
The piano is not typically found in a symphony orchestra, unlike the violin, trumpet, and cello. Flute and oboe are examples of open-pipe resonators, and they alter pitch by changing the length of their resonating tubes.
Step-by-step explanation:
The instrument that is not typically found in a symphony orchestra among the ones listed is the piano. Violins, trumpets, and cellos are standard instruments found within an orchestra. The violin and cello are stringed instruments, while the trumpet is a brass instrument. The piano is less commonly part of the main orchestra setup, although it is occasionally used for specific compositions. In an orchestra, players tune their instruments, with woodwind instruments producing high-frequency notes and stringed instruments often producing a wider range of notes.
As for open-pipe resonators, examples include the flute and oboe, both of which are aerophones. Instruments like the flute or oboe change the length of the resonating tube by opening and closing finger holes, affecting the pitch of the sound produced. This illustrates how the physical properties of an instrument, like size and shape, impact the frequency and pitch of the sounds it produces.