Final answer:
The Doppler effect refers to the change in frequency or wavelength due to the relative movement between a wave source and an observer. It applies to all types of waves, not just sound. A pebble dropping in water is an example of a pulse wave, and different frequencies can superimpose, creating wave interference.
Step-by-step explanation:
The Doppler effect is a change in frequency or wavelength of a wave in relation to an observer who is moving relative to the wave source. It applies not only to sound waves but to any type of wave, including light waves. An example of the Doppler effect is the change in pitch of a siren as an ambulance drives by. The frequency will become higher as the source of the sound approaches the observer and lower as it moves away.
A pulse wave generated by dropping a pebble in water is indeed a real example of a pulse wave. In the context of cardiac physiology, the placement of a stethoscope's bell is crucial for auscultation, allowing the listener to hear different heart valves at specific locations on the chest. Additionally, in medical diagnostics, Doppler shifts are used in ultrasound techniques to determine blood velocity by reflecting sound off of moving blood cells.
It's also false to say that the observed frequency becomes infinite when the source is moving at the speed of sound; rather, a sonic boom occurs. Furthermore, it's true that waves can superimpose even if their frequencies are different, creating instances of constructive or destructive interference. Lastly, the position vs time graph of an object that is speeding up is not a straight line; this represents acceleration and would be a curve on the graph.