A train moving east at a velocity of 20 m/s emits a whistle at a frequency of 348 Hz. Another train, farther up the track and moving east at a velocity of 30 m/s, hears the whistle from the first train. (a) If the speed of sound in air is 343 m/s, what is the frequency of the sound heard by the second train engineer? (b) What is the frequency of the echo heard by the first train engineer coming off the second train?
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 train moving east at a velocity of 20 m/s emits a whistle at a frequency of
348 Hz. Another train, farther up the track and moving east at a velocity of
30 m/s, hears the whistle from the first train. (a) If the speed of sound in air
is 343 m/s, what is the frequency of the sound heard by the second train
engineer? (b) What is the frequency of the echo heard by the first train
engineer coming off the second train?
Trending now
This is a popular solution!
Step by step
Solved in 2 steps
