A firetruck at rest is producing a siren of frequency 450HZ. If the observer A, is moving away from the truck with a speed of 20 m/s, then the frequency heard by him will be 1. Observer B Observer A (a) Firetruck at rest a. 900 Hz b. equal to 450 Hz O c. less than 450 Hz O d. more than 450 Hz
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 firetruck at rest is producing a siren of freguency 450HZ. If the observer A, is moving away from the truck
with a speed of 20 m/s, then the frequency heard by him will be
Observer B
Observer A
(a) Firetruck at rest
a.
900 Hz
O b. equal to 450 Hz
c.
less than 450 Hz.
d. more than 450 Hz](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fb60fd19b-3f24-4c4a-bc73-bcdf607d62f4%2F7d08241b-9a86-4ded-b171-25ab67ace021%2Fvybywii_processed.jpeg&w=3840&q=75)
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