Explain why an ambulance siren sounds like it has a higher pitch when it moves towards you but a lower pitch?

Question

as it moves away from you. How de we know when a star in the galaxy is moving towards us? what color will it appear to be? what do these examples have in common?

Answer 1

This is due to the Doppler Effect. When sound changes wavelength we hear a difference in pitch, when this effect happens with light we see a difference in color (colors get "red shifted" when objects are moving away, and "blue shifted" when they are coming at us). Since the speed of light is much faster than the speed of sound, we hear the siren change pitch but we don't notice the ambulence change color (it would have to be going hundreds of thousands of mph for this to be noticeable).

Answer 2

The apparent change in frequency due to the relative motion between the source and observer is called Doppler Effect.This effect is the reason for your question. Let us consider the velocity of sound be V m/ s and that of the ambulance be Va m/s. Let the frequency be n Hz and the wave length be L m. Then we can write v =nL. As the ambulance is moving towards the observer after 1 second the distance traveled becomes V-Va m. In between the first and last wave produced there are n waves .Therefore the wave length becomes L" =V-Va / n m. the apparent frequency n* = V/ L*. n* = (V/ V-Va ) n . When the ambulance moves away the relation becomes n* = (V/V+Va)n.Hope this will clear your doubt.

Answer 3

Its called the Doppler effect.

Imagine the sound waves from the siren. As it comes closer, the sound waves are compressed by the vehicle approaching. As the siren leaves you, the sound waves are being stretched out.

So it has a higher pitch coming and a lower pitch going.

The same with the stars. If they are coming closer there is a compression, etc.

Answer 4

The sound frequency as it's approaching is increasing in pitch and, as it's moving away it's decreasing .. it's called the 'Doppler Effect'.
The same principle (though soundless) is also used with radar waves (used by the police to catch you speeding).

With reference to a star, if it's receding, the wavelength of the light is increasing, and opposite if approaching.
Scientists can measure the difference.

Answer 5

ok, enable's take this one step at a time... a million. mild from a techniques away galaxies is purple-shifted, meaning the galaxies are all shifting remote from us. (in the event that they have been shifting nearer to us, they could be blue-shifted.) 2. The farther away a galaxy is, the swifter it is shifting remote from us. 3. The universe is increasing. 4. Cosmic microwave history is the temperature of the vacuum of area. it is approximately 3 ranges Kelvin, -- i.e., just about absolute 0, the coldest obtainable temperature -- so the universe ought to have cooled off plenty after the super Bang. 5. Many scientists have self belief in the super Bang concept for the beginning place of the universe, additionally prevalent as cosmology. i'm hoping this helps, a minimum of in elementary terms somewhat.

Answer 6

The pitch depends upon the rate at which the vibrations are reaching you. If the source is moving towards you, the rate of received vibrations is increasing, and conversely.

Answer 7

the doppler effect