1) Are ultrasound and infrasound imperceptible to all hearing organisms? Explain your answer.
2) You observe two musical instruments that you cannot identify. One plays high-pitch sounds. How could you determine which is which without hearing either of them play?
3) Why did scientist Christian Doppler observe musicians both on a moving train and also from a stationary point not on a train?
4) Describe a situation in your life when you might rely on the Doppler shift to help you either while driving a car or walking near a traffic.
ADDITIONAL:
Imagine you observe two fireworks explode. You hear the explosion of one as soon as you see it. However, you see the other firework for several milliseconds before you hear the explosion. Explain why this is so.
2) You observe two musical instruments that you cannot identify. One plays high-pitch sounds. How could you determine which is which without hearing either of them play?
3) Why did scientist Christian Doppler observe musicians both on a moving train and also from a stationary point not on a train?
4) Describe a situation in your life when you might rely on the Doppler shift to help you either while driving a car or walking near a traffic.
ADDITIONAL:
Imagine you observe two fireworks explode. You hear the explosion of one as soon as you see it. However, you see the other firework for several milliseconds before you hear the explosion. Explain why this is so.
Answers & Comments
Verified answer
1) No, the range of perceptible sound is based in the range of human hearing. Many other organisms perceive either infrasound or ultrasound.
2) Compare their sizes. High-pitch instruments are generally smaller than low-pitch instruments because they generate a smaller wavelength.
3) Doppler needed to compare the perception of sound when the observer is stationary and the sound source moves, as well as when the sound source and the observer are both in motion.
4) If I am driving and I hear doppler shift in an ambulance siren, I would be able to tell when it was getting closer and also if it has passed by. This would help me to know whether I needed to pull over and let the ambulance through.
Question:
Imagine you observe two fireworks explode. You hear the explosion of one as soon as you see it. However, you see the other firework for several milliseconds before you hear the explosion. Explain why this is so.
Answer:
Sound and light both travel at definite speeds. The speed of sound is slower than the speed of light. The first firework is probably very close by, so the speed difference is not noticeable. The second firework is farther away, so the light arrives at your eyes noticeably sooner than the sound wave arrives at your ears.