Estimating Jet Speed Using Sound and Light

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Homework Help Overview

The discussion revolves around estimating the speed of a jet aircraft flying at an altitude of 10,000 meters, particularly focusing on the relationship between the speed of sound and the speed of light as perceived by an observer on the ground.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the implications of the speed of sound being slower than the speed of light, referencing personal experiences and classroom learning. There are attempts to connect these concepts to the scenario of a jet flying overhead.

Discussion Status

Some participants are exploring how to estimate the jet's speed using the information provided, while others note the need for additional data to arrive at a solution. There is a hint of guidance from a teacher regarding the use of a stopwatch, but no consensus or clear method has emerged yet.

Contextual Notes

Participants mention the lack of sufficient data to calculate the speed accurately and reference the concept of traveling at or above the speed of sound (1 mach).

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Homework Statement



When a jet plane flies overhead at a high altitude, the sound from the engines can be heard, but the sound seems to come from well behind the aircraft. If you knew the altitude of the jet to be 10,000m, how could you estimate the speed of it? Show this using an example.

Homework Equations



c = 3.00*10^8m/s?

The Attempt at a Solution



I asked my teacher this question, but he told me to think about it. He hinted at using the speed of light, speed of sound, and a stop watch. I tried drawing a diagram showing how the person would see the plane first before hearing the engine. I know sound travels slower than light, but I don't know what to do next.
 
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The aircraft is traveling faster than the speed of the sound. Another good example of this is lightning and thunder. You see the lightning first because the speed of light is faster than the speed of sound (the thunder). In my class of physics 11 we finished that module last week.
 
Johnny Blade said:
The aircraft is traveling faster than the speed of the sound. Another good example of this is lightning and thunder. You see the lightning first because the speed of light is faster than the speed of sound (the thunder). In my class of physics 11 we finished that module last week.

Thanks for the answer, but is there a way to estimate the speed of the jet?
 
Not if there's no more data. The speed is 1 mach or higher.
 
I think it can be figured out because as I previously posted, my teacher hinted at using the speed of sound, speed of light, and a stop watch.
 
Does anyone have a solution?
 

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