Confused by Mark Scheme: Exam Q on Fire Engine Sound Wave

In summary, the conversation discusses the confusion surrounding a question about the pitch of a siren on a moving fire engine. The individual initially believed that the wavelength of the sound wave decreases, but the mark scheme stated that the distance traveled by each wave front increases. Later, when faced with a similar question, the individual's explanation matched that of the mark scheme. They question whether their initial answer was correct or if the mark scheme has a discrepancy in its standards.
  • #1
Luke1121
14
0
I've just finished some past exam papers and when marking them using the mark scheme something confused me a little
One question said when a fire engine moves away from an observer, the pitch of the siren decreased, why and I chose the wavelength of the sound wave decreases
The mark scheme said the answer was the distance traveled by each wave front increases
I learned from my mistake and moved on. Today I've done another paper and a question says explain how the movement of the ambulance causes the frequency of the sound the man hears to change. Remembering my mistakes I talked about as the ambulance moves closer the distance traveled by each wavefront, decreases so there are more waves per second so f increases and the opposite for moving away, but the mark scheme said "higher frequency, wavelengths shorter as ambulance moves closer" Am I actually correct in what I'm saying or has the mark scheme got a case of double standards. Thanks in advance.
 
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  • #2
Those answers look like different ways of expressing the same thing.

Personally, I'd focus on the the motion of the sound source decreasing the distance between wave fronts in the direction of motion and decreasing it behind.
 

What is a fire engine sound wave?

A fire engine sound wave is a type of sound wave produced by the siren of a fire engine. It is a type of longitudinal wave that travels through the air and is perceived by our ears as a loud, high-pitched sound.

Why is the fire engine sound wave confusing in a Mark Scheme?

The fire engine sound wave can be confusing in a Mark Scheme because it involves multiple concepts from physics, such as wave properties, frequency, and amplitude. Additionally, the question may require the application of mathematical equations and conversions, which can add to the confusion.

What factors affect the frequency of a fire engine sound wave?

The frequency of a fire engine sound wave can be affected by the speed of the fire engine, the number of times the siren rotates, and the distance between the siren and the observer. Additionally, the Doppler effect can also impact the perceived frequency of the sound wave.

How does the Doppler effect impact the fire engine sound wave?

The Doppler effect occurs when there is relative motion between the source of the sound wave and the observer. This can cause a change in the perceived frequency of the sound wave. In the case of a fire engine, as it approaches an observer, the sound waves will have a higher frequency, and as it moves away, the frequency will decrease.

What are some real-world applications of understanding the fire engine sound wave?

Understanding the fire engine sound wave can be helpful in designing more effective emergency sirens. It can also be used in noise pollution studies to measure the impact of loud sounds on the environment and human health. Additionally, understanding sound waves can lead to advancements in medical imaging and acoustic technologies.

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