Question

1. The pitch of the siren of a moving fire truck changes from high to low as the fire truck passes by. What property of a sound wave changes as the fire truck goes by?
A. Amplitude
B. Density
C. Temperature
D. Frequency

2. Sonar is used to inspect pipelines and bridge foundations. In this scenario, sonar takes advantage of the fact that
A. sound waves can reflect
B. sound waves can diffract
C. sound waves can spread out.
D. sound waves can refract