Refer to the following information for the next six questions.
Vibration graph of point P

Waveform graph at t = 10 seconds (P is at 10 cm)

Refer to the following information for the next seven questions.
Vibration graph of point Q

Waveform graph at t = 10 seconds (Q is at 20 cm)

Refer to the following information for the next two questions.
