I need help with this science question?

Question

While you are standing at a train station, a train approaches, sounding it's whistle. You notice that, as the train gets very close, the pitch of it's whistle sounds higher. What is the explanation for the change in sound?

a.) the frequency of the whistle increases as the train approaches

b.) the wavelength decreases as the train gets closer

c.) the wavelength increases as the train gets closer

d.) the frequency of the whistle decreases as the train gets closer

please explain your steps. thank you.

Answer 1

Frequency increases and wavelength decrease. a & b

Answer 2

ANSWER IS ...(A)

It is due to doppler effect

A change in the observed frequency of a wave, as of sound or light, occurring when the source and observer are in motion relative to each other, with the frequency increasing when the source and observer approach each other and decreasing when they move apart. The motion of the source causes a real shift in frequency of the wave, while the motion of the observer produces only an apparent shift in frequency. Also called Doppler shift.

           Sound and light are both examples of energy, and both are carried on waves. Wave motion is a type of harmonic motion that carries energy from one place to another without actually moving any matter. It is related to oscillation, a type of harmonic motion in one or more dimensions. Oscillation involves no net movement, only movement in place; yet individual points in the wave medium are oscillating even as the overall wave pattern moves.

n 1 more point frequency is inversely proportional to wavelength

Answer 3

The answer is B. As sound waves emanate from a source they lengthen. The larger wavelengths have low tones, so from far away the train whistle sounds lower. As the train approaches the tone gets higher because the wavelengths are shorter. Frequency has nothing to do with the increased pitch. Frequency maintains constant no matter where it is or how how far away it is.

Answer 4

For any wave, velocity = freq x wavelength. Given that velocity is fixed (in a given medium) if the pitch (i.e. frequency) of the wave increases, then the wavelength must decrease (shorten).

In this case pitch (i.e frequency) rises and wavelength decreases. I'd never have the two anwers in one of my tests. However answer b is the more correct as the motion of the train effectively compresses the wavelength as it approaches. After the train passes, the percieved pitch drops as the departing train "stretches" the wavelength longer. The rise in pitch is a secondary effect of the change in wavelength.

Answer 5

Frequency of sound affects the pitch thats why the answer shld be A

Answer 6

DOPPLER EFFECT. I think. Picture sound waves flying off the train. As it gets closer, the waves get smooshed which is a shorter wavelength and therefore higher pitch. When it goes by the waves get strung out more and make a lower pitch. So (b) i think.