A car approaches a reflecting wall. An observer at rest, situated behind the car, hears a sound of frequency f₁ from the car horn and a sound of frequency f₂ coming from the wall. (a) What is the ratio of the speed of the car to the speed of sound in air in terms of f₁ and f₂? (b) What is the frequency of the car horn in terms of f₁ and f₂? (c) Consider now that the local speed of sound is worth 340 m/s, and that the car horn has a frequency of 500 Hz. If the observer hears 30 beats per second, what is the speed of the car?
Properties of sound
A sound wave is a mechanical wave (or mechanical vibration) that transit through media such as gas (air), liquid (water), and solid (wood).
Quality Of Sound
A sound or a sound wave is defined as the energy produced due to the vibrations of particles in a medium. When any medium produces a disturbance or vibrations, it causes a movement in the air particles which produces sound waves. Molecules in the air vibrate about a certain average position and create compressions and rarefactions. This is called pitch which is defined as the frequency of sound. The frequency is defined as the number of oscillations in pressure per second.
Categories of Sound Wave
People perceive sound in different ways, like a medico student takes sound as vibration produced by objects reaching the human eardrum. A physicist perceives sound as vibration produced by an object, which produces disturbances in nearby air molecules that travel further. Both of them describe it as vibration generated by an object, the difference is one talks about how it is received and other deals with how it travels and propagates across various mediums.
A car approaches a reflecting wall. An observer at rest, situated behind the car, hears a sound of frequency f₁ from the car horn and a sound of frequency f₂ coming from the wall. (a) What is the ratio of the speed of the car to the speed of sound in air in terms of f₁ and f₂? (b) What is the frequency of the car horn in terms of f₁ and f₂? (c) Consider now that the local speed of sound is worth 340 m/s, and that the car horn has a frequency of 500 Hz. If the observer hears 30 beats per second, what is the speed of the car?
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