Which are examples of resonance? check all that apply. the volume on a stereo being turned up a note being played on a saxophone an opera singer breaking a glass with her voice a person pushing a swing at the rate it naturally oscillates back and forth an echo

-A note being played on a saxophone

-An opera singer breaking a glass with her voice

-A person pushing a swing at the rate it naturally oscillates back and forth

Explanation:

Resonance describes the phenomena of amplification that occurs when the frequency of a periodically applied force is in harmonic proportion to a natural frequency of the system on which it acts.

In all the stated examples we have system with a natural frequency and a oscillating force being applied in harmonic proportion to the referred natural frequency. In the saxophone the blowing and the position of the fingers in the instrument is done to amplify a certain note, in the case of the opera singer the force of the wave sounds is harmonically proportional with the glass frequency causing it to vibrate harder until it breaks. In the swing case the person's forces is the force in proportion with the swing natural frequency

t = 1/400 h   ⇔ 0.0025 h ⇔ 9s ⇔ 0.15 m

any of the answers are correct.